Chemotherapy-induced changes and immunosenescence of CD8+ T-cells in patients with breast cancer

BACKGROUND

Changes in sub-populations of cytotoxic (CD8+) T-cells, which are observed in aging and in conditions of chronic immune stimulation, are not well-documented in cancer.

MATERIALS AND METHODS

Using flow cytometry, CD8+ T-cell subsets were analyzed in patients with breast cancer undergoing DNA-damaging chemotherapy and in an older female control group during a six-month longitudinal study, to explore shifts in CD8+ T-cells and the effect of DNA-damaging chemotherapy on different T-cell sub-populations.

RESULTS

As expected, there was a consistent decrease in absolute numbers of leukocytes, lymphocytes, T-cells and CD8+ T-cells during chemotherapy in patients with cancer. Among the T-cells, there was a lower CD8-/CD8+ ratio, persisting over the six months, in patients with cancer compared to controls. The proportion of CD28-CD57+ cells also remained higher among patients with cancer throughout the sampling duration. The number of CD28+CD57- and CD28-CD5- cells decreased faster during DNA-damaging chemotherapy than CD28+CD57+ and CD28-CD57+ cells, while only CD28-CD57- cells showed a significant reconstitutive capacity after six months.

CONCLUSION

Immunosenescence appeared to be pronounced in patients with breast cancer, with senescent CD8+ T-cells playing a role. The normal condition was not restored after six months of chemotherapy.

TNFα polymorphism as marker of immunosenescence for rheumatoid arthritis patients

BACKGROUND

Expansion of CD4(+)CD28(null), a common feature of immunosenescence, which has been reported in rheumatoid arthritis (RA) patients, may also be associated with a CD4(+) imbalance. Although the increase of CD4(+)CD28(null) cells has been related to TNFα exposure, nothing is known about the possible role of genetic variants of this cytokine.

METHODS

Participants were genotyped for TNFA rs1800629 (-308 G>A) and frequency of the CD4(+)CD28(null), regulatory T cells and Th1 cells subsets were quantified in peripheral blood samples by flow cytometry in 129 RA patients and 33 healthy controls.

RESULTS

The expansion of CD4(+)CD28(null) cells in RA patients was associated with TNFA genotype, even at diagnosis, and linked to markers of aggressive disease in patient carriers of the minor allele. Analysis of regulatory T cells and IFNγ-CD4(+) expression suggested that defective suppression and/or Th1-shift could underlie the expansion of this population in these patients. Finally, although treatment with TNFα-blockers reduced CD4(+)CD28(null) cells in most patients, only those carriers of the common GG genotype reached values within the range of HC and showed a disease activity improvement correlated to this decrease.

CONCLUSIONS

Our results provide evidence for a genetic basis of the premature immunosenescence of RA patients and highlight its potential role in clinical outcome after TNFα blockade.

Comparison of changes in the percentages of CD8+CD28-TCRalpha beta+ T cell subpopulations in allergic asthma subjects vs controls before and after anti-CD3/anti-CD28/IL-2 stimulation in vitro

Asthma is a chronic inflammatory disease characterized by the migration of activated T cells into the bronchial mucosa. TGF-beta and IL-10 have proved to regulate airway hyper-responsiveness and leukocytes recruitment to the airways of ovalbumin (OVA) sensitized mice. We examined relative changes in CD8+T cell subpopulations between fifty allergic asthma subjects and twenty five aged-matched healthy adults before and after anti-CD3/CD28 and IL-2 stimulation in the presence of IL-10 or TGF-beta, focusing on CD62L and FoxP3 expressing TCR alpha beta + cells. Severe asthma group had a significantly higher percentage of CD8+ CD28-and CD8+ CD28-TCR alpha beta + CD62L highFoxP3 bright T cells than other groups after enrichment. Compared to the baseline, co-stimulation with either IL-10 or TGF-beta increased the percentage of CD8+CD28-but decrease the percentage of CD8+CD28+T cells within anti-CD3/anti-CD28/IL-2 activated CD8+T cells in all groups. Co-stimulation with anti-CD3/anti-CD28/IL-2 in presence of either IL-10 or TGF-beta decreased the frequencies of CD8+CD28-TCR alpha beta +CD62Lhigh FoxP3 bright T cells in severe asthma subgroup but increased this parameter in other groups. We suggest that altered high level expression of CD62L and FoxP3 on CD8+ CD28-TCR alpha beta + T cell is relevant to allergic asthma. These data have implications for further characterization of CD8+ CD28-TCR alpha beta+ T cell subsets, with special emphasis on their implication in healthy or allergic immune response.

The effects of interleukin-10 or TGF-beta on anti-CD3/CD28 induced activation of CD8+CD28- and CD8+CD28+ T cells in allergic asthma

The CD8+CD28- and CD8+CD28+ T cells play a primordial role in peripheral tolerance, but little is known about their implication in allergic asthma. This study was designed to determine the changes in a proportion of human circulatory CD8+ subsets before and after short term culture in the presence of anti-CD3/CD28 and IL-10 or TGF-beta. Flow cytometry analysis revealed increased percentage of CD8+CD28- T cells but decreased percentage of CD8+CD28+ T cells enriched from peripheral blood of adult allergic asthma individuals compared to controls (baseline). In comparison to the baseline, co-stimulation with anti-CD3/CD28 and IL-10 decreased the proportion of CD8+CD28- T cells in severe allergic asthma subjects, whereas it increased this value in mild to moderate asthmatic subjects and controls. Adding TGF-beta decreased the proportion of CD8+CD28- T cells from allergic asthma subjects, whereas it has opposite effects on this subset from controls. IL-10 and TGF-beta had some plethoric effects on FoxP3 expression in anti-CD3/CD28 activated CD8+CD28- T cells. Thus, these findings indicate that a control mechanism involving IL-10 and TGF-beta might be defective in allergic asthma subjects.

The "time-window" effect of early allergen exposure on a rat asthma model

BACKGROUND

The hygiene hypothesis has been proposed to explain the pathogenesis of asthma. Allergen exposure was shown to inhibit asthma in an animal model. But the optimal timing of allergen exposure remains unclear. This study aims to explore the time effcct of allergen exposure and the possible mechanisms.

METHODS

Neonate Wistar rats were randomly divided into asthma group, control group and day 1, day 3, day 7, and day 14 groups. The day 1, day 3, day 7 and day 14 groups were injected with ovalbumin (OVA) subcutaneously on days 1, 3, 7 and 14 after birth, respectively. Six weeks later, all groups, except the control group, were sensitized and stimulated with OVA to make the asthma model. We observed the pulmonary pathologic changes, detected the regulatory T cells, and CD28 expression level in thymus and spleen by flow cytometry.

RESULTS

The asthmatic inflammation in the day 1, day 3 and day 7 groups, but not the day 14 group, was alleviated. The asthma group and day 14 group had lower proportions of regulatory T cells in the thymus compared with the control group, day 1, day 3, and day 7 groups. There was no significant difference in the CD28 expression levels on the regulatory and conventional T cells among groups. But the control group and the day 1, day 3, and day 7 groups had relatively higher proportions of CD28 positive regulatory T cells in the thymus than the day 14 group and the asthma group.

CONCLUSIONS

There is a "time-window" for early allergen exposure. The impairment of regulatory T cells may promote the development of asthma. Allergen exposure in the "time-window" can make the thymus produce normal quantity of regulatory cells. The CD28 signal on regulatory T cells may participate in the production of regulatory T cells.

Expression of NKG2D and CD107 in CD8(+) effector memory lymphocytes in Churg-Strauss syndrome

OBJECTIVES

Churg-Strauss syndrome (CSS) is a necrotising vasculitis of small vessels in which oligoclonally expanded TCR Vβ CD8+ effector memory T cells populations (TEM) may be involved in vasculitic damage. The aim of this study was to assess the functional role of CD8+ T cells in CSS patients by flow cytometry analysis of membrane expression of cytotoxic markers NKG2D and CD107a.

METHODS

Immunostaining of peripheral T cells and effector memory lymphocytes (TEM) from CSS patients and controls was performed by gating CD28 and CD45RA in the CD8+NKG2D+ and CD4+NKG2D+ populations. CD107a expression was evaluated in both whole CD8+ and CD4+ and the TEM cells by gating CD62 and CD45RA following polyclonal stimulation.

RESULTS

NKG2D expression was shifted toward the CD8+CD28- fraction of T cells in CSS patients compared to healthy controls (56.1±25.8% versus 17.2±7.3%, respectively, p=0.002). CD8+Vβ+ expanded T cells showed a significantly increased expression of NKG2D compared to the whole CD8+ T cell population (91.4±1.9% versus 79.7±3.8%, respectively, p=0.015). Moreover the CD8+ population from CSS upregulates CD107a on its surface upon polyclonal stimulation in a significantly higher proportion than healthy subjects (26.2±10.8% versus 8.2±2.9%, p=0.0031) and the majority CD8+ CD107+ cells from CSS patients showed a TEM phenotype compared to controls (64.8±4.9% vs. 19.8±2.9, respectively, p<0.001).

CONCLUSIONS

In CSS, CD8+ TEM lymphocytes show markers of cytotoxic activity, which suggests a role for these cells in vasculitic damage.

Cellular aging and senescence characteristics of human T-lymphocytes

CD28-, CD57+ and KLRG1+ are cell surface markers that have been used to describe senescent T-lymphocytes in humans. However, the relationship among these phenotypes during aging, and their relationship with the concept of in vitro cellular aging have not been well established. Using five-colour flow cytometry, we analyzed peripheral blood T-lymphocytes for their expression of CD28, CD57 and KLRG1 in 11 young (Y) and 11 old (O) apparently healthy human subjects. The proportions of CD28- and CD57+ cells were significantly higher among the T-cell populations of O compared to Y subjects; the proportion of KLRG1+ cells was significantly higher only among CD8+ cells. Populations that were more frequent in the elderly participants were characterised as CD28+ CD57+, CD28- CD57+ or CD28- CD57-. The expression of p16 and p21, considered as markers for in vitro senescence, was higher in CD28+ CD57+ cells than in other subpopulations in both age groups. The expression of p21 was age-related, which was not the case for p16. Thus, although both p16 and p21 are involved in T-cell senescence, they appear to behave differently. CMV infection and shifts in subpopulations are unlikely as explanations of the observed differences. Their higher levels of p16 and p21 expression, coupled with their higher prevalence in the elderly participants make CD28+ CD57+ cells the subpopulation of T-cells most closely corresponding to the concept of senescent cells.

IL-15 preferentially enhances functional properties and antigen-specific responses of CD4+CD28(null) compared to CD4+CD28+ T cells

One of the most prominent changes during T-cell aging in humans is the accumulation of CD28(null) T cells, mainly CD8+ and also CD4+ T cells. Enhancing the functional properties of these cells may be important as they provide an antigen-specific defense against chronic infections. Recent studies have shown that IL-15 does in fact play an appreciable role in CD4 memory T cells under physiological conditions. We found that treatment with IL-15 increased the frequency of elderly CD4+CD28(null) T cells by the preferential proliferation of these cells compared to CD4+CD28+ T cells. IL-15 induced an activated phenotype in CD4+CD28(null) T cells. Although the surface expression of IL-15R α-chain was not increased, the transcription factor STAT-5 was preferentially activated. IL-15 augmented the cytotoxic properties of CD4+CD28(null) T cells by increasing both the mRNA transcription and storage of granzyme B and perforin for the cytolytic effector functions. Moreover, pretreatment of CD4+CD28(null) T cells with IL-15 displayed a synergistic effect on the IFN-γ production in CMV-specific responses, which was not observed in CD4+CD28+ T cells. IL-15 could play a role enhancing the effector response of CD4+CD28(null) T cells against their specific chronic antigens.

Comparison of DNA vaccines producing HIV-1 Gag and LAMP/Gag chimera in rhesus macaques reveals antigen-specific T-cell responses with distinct phenotypes

Optimized DNA expression vectors encoding the native HIV-1 Gag or a fusion of Gag with the lysosomal membrane associated protein 1 (LAMP) were compared for immunogenicity upon intramuscular DNA delivery in rhesus macaques. Both vaccines elicited CD4(+) T-cell responses, but with significant differences in the phenotype of the Gag-specific cells: the native Gag induced CD4(+) responses with a phenotype of central memory-like T cells (CD28(+) CD45RA(-)), whereas the LAMP/Gag chimera induced CD4(+) responses with effector memory phenotype (CD28(-) CD45RA(-)). Antigen-specific T cells producing both IFN-gamma and TNFalpha were found in the animals receiving the native Gag, whereas the LAMP/Gag chimera induced humoral responses faster. These results demonstrate that modification of intracellular Gag trafficking results in the induction of distinct immune responses. Combinations of DNA vectors encoding both forms of antigen may be more potent in eliciting anti-HIV-1 immunity.

Microarray analysis reveals similarity between CD8+CD28- T cells from young and elderly persons, but not of CD8+CD28+ T cells

We isolated highly purified CD8+CD28+ and CD8+CD28- T cell populations from healthy young and elderly persons for gene expression profiling using Affymetrix oligonucleotide microarrays. We demonstrate that the gene expression profile of CD8+CD28- T cells is very similar in young and elderly persons. In contrast, CD8+CD28+ in elderly differ from CD8+CD28+ in young persons. Hierarchical clustering revealed that CD8+CD28+ in elderly are located between CD8+CD28+ in young and CD8+CD28- (young and old) T cells regarding their differentiation state. Our study demonstrates a dichotomy of gene expression levels between CD8+CD28+ T cells in young and elderly persons but a similarity between CD8+CD28- T cells in young and elderly persons. As CD8+CD28+ T cells from elderly and young persons are distinct due to a different composition of the population, these results suggest that the gene expression profile does not depend on chronological age but depends on the differentiation state of the individual cell types.

Skewed distribution of proinflammatory CD4+CD28null T cells in rheumatoid arthritis

Expanded populations of CD4+ T cells lacking the co-stimulatory molecule CD28 (CD4+CD28null T cells) have been reported in several inflammatory disorders. In rheumatoid arthritis, increased frequencies of CD4+CD28null T cells in peripheral blood have previously been associated with extra-articular manifestations and human cytomegalovirus (HCMV) infection, but their presence in and contribution to joint manifestations is not clear. In the present article we investigated the distribution of CD4+CD28null T cells in the synovial membrane, synovial fluid and peripheral blood of RA patients, and analysed the association with erosive disease and anti-citrullinated protein antibodies. CD4+CD28null T cells were infrequent in the synovial membrane and synovial fluid, despite significant frequencies in the circulation. Strikingly, the dominant TCR-Vbeta subsets of CD4+CD28null T cells in peripheral blood were often absent in synovial fluid. CD4+CD28null T cells in blood and synovial fluid showed specificity for HCMV antigens, and their presence was clearly associated with HCMV seropositivity but not with anti-citrullinated protein antibodies in the serum or synovial fluid, nor with erosive disease. Together these data imply a primary role for CD4+CD28null T cells in manifestations elsewhere than in the joints of patients with HCMV-seropositive rheumatoid arthritis.

Flow cytometric detection of degranulation reveals phenotypic heterogeneity of degranulating CMV-specific CD8+ T lymphocytes in rhesus macaques

Flow-cytometric conditions for detection of lysosomal-associated membrane proteins (LAMPs) on the surface of recently degranulated cells were optimized for rhesus macaques and used to investigate the functional properties of rhesus cytomegalovirus (rhCMV)-specific CD8+ T lymphocytes with regards to cytotoxicity and interferon (IFN)-gamma secretion in six asymptomatic CMV-seropositive rhesus macaques. Unlike humans, the rhesus macaque LAMP-1 protein CD107a underwent little or no endocytosis over a six to 18 h stimulation period. Following in vitro stimulation, rhCMV-specific CD8+ T lymphocytes were heterogeneous with regards to the composition of cells positive for CD107a and/or IFN-gamma, time to reach peak degranulation, and kinetics of IFN-gamma secretion relative to degranulation. Responder CD8+ T lymphocytes that underwent degranulation without IFN-gamma production (CD107a+IFN-gamma-) were predominantly composed of terminally differentiated effectors (CD28-CD45RA+). Moreover, they had significantly lower frequencies of effector memory (CD28-CD45RA-) cells compared to the IFN-gamma-secreting cells that did or did not undergo degranulation (CD107a+IFN-gamma+ or CD107a-IFN-gamma+). The perforin content of effector CD8+ T lymphocytes was significantly greater than that of effector memory CD8+ T lymphocytes in rhesus macaques, suggesting that they were more cytolytic. Our findings suggest that the composition of rhCMV-specific CD8+ T lymphocytes with regards to CD107a+IFN-gamma- responders may be an important determinant of their ability to control CMV replication.

The loss of telomerase activity in highly differentiated CD8+CD28-CD27- T cells is associated with decreased Akt (Ser473) phosphorylation

The enzyme telomerase is essential for maintaining the replicative capacity of memory T cells. Although CD28 costimulatory signals can up-regulate telomerase activity, human CD8(+) T cells lose CD28 expression after repeated activation. Nevertheless, telomerase is still inducible in CD8(+)CD28(-) T cells. To identify alternative costimulatory pathways that may be involved, we introduced chimeric receptors containing the signaling domains of CD28, CD27, CD137, CD134, and ICOS in series with the CD3 zeta (zeta) chain into primary human CD8(+) T cells. Although CD3 zeta-chain signals alone were ineffective, triggering of all the other constructs induced proliferation and telomerase activity. However, not all CD8(+)CD28(-) T cells could up-regulate this enzyme. The further fractionation of CD8(+)CD28(-) T cells into CD8(+)CD28(-) CD27(+) and CD8(+)CD28(-)CD27(-) subsets showed that the latter had significantly shorter telomeres and extremely poor telomerase activity. The restoration of CD28 signaling in CD8(+)CD28(-)CD27(-) T cells could not reverse the low telomerase activity that was not due to decreased expression of human telomerase reverse transcriptase, the enzyme catalytic subunit. Instead, the defect was associated with decreased phosphorylation of the kinase Akt, that phosphorylates human telomerase reverse transcriptase to induce telomerase activity. Furthermore, the defective Akt phosphorylation in these cells was specific for the Ser(473) but not the Thr(308) phosphorylation site of this molecule. Telomerase down-regulation in highly differentiated CD8(+)CD28(-)CD27(-) T cells marks their inexorable progress toward a replicative end stage after activation. This limits the ability of memory CD8(+) T cells to be maintained by continuous proliferation in vivo.

In vitro generation of CD4+CD25+ regulatory cells from murine naive T cells

CD4+ CD25+ regulatory T cells (Tregs) are crucial for the maintenance of immunological tolerance. Recent data indicate that Tregs not only develop in the thymus during ontogeny but can also differentiate from naive T cells in the periphery. The following protocol describes a method by which Tregs are generated in vitro by stimulation of naive T cells in the presence of transforming growth factor beta (Ti-Tregs). In vitro-induced regulatory T cells express markers of conventional Treg such as CD25 and the genetic program committing transcription factor FoxP3. Functionally the in vitro-generated Ti-Tregs suppress T-cell activation and proliferation while in vivo these cells have been proven to control inflammation in different animal models, suggesting a potential use of these cells for immunotherapy. The protocol can be completed within 5 days.

Transfer of in vitro expanded T lymphocytes after activation with dendritomas prolonged survival of mice challenged with EL4 tumor cells

Adoptive T cell transfer after in vitro expansion represents an attractive cancer immunotherapy. The majority of studies so far have been focusing on the expansion of tumor infiltrated lymphocytes (TIL) and some have shown very encouraging results. Recently, we have developed a unique tumor immune response activator, dendritomas, by fusion of dendritic cells and tumor cells. Animal studies and early clinical trials have shown that dendritomas are able to activate tumor specific immune responses. In this study, we hypothesized that naïve T cells can be primed with dendritomas and expanded in vitro to develop an adoptive transfer therapy for patients who do not have solid tumors, such as leukemia. T cells were isolated and purified from lymph nodes of mice. The cells were then incubated with dendritomas made from syngeneic DCs and tumor cells and expanded in vitro using Dynabeads mouse CD3/CD28 T cell expander for approximately three weeks. The in vitro primed and expanded T cells showed tumor cell specific CTL activity and increased secretion of IFN-gamma. Tumor bearing mice receiving the in vitro expanded T cells survived significantly longer than control mice. Furthermore, the depletion of regulator T cells enhanced the survival of the mice that received the adoptive transfer therapy.

High-intensity exercise elicits the mobilization of senescent T lymphocytes into the peripheral blood compartment in human subjects

Clonal expansion of T lymphocytes in response to antigenic stimulation is a fundamental process of adaptive immunity. As a consequence of clonal expansion, some T lymphocytes acquire a senescent phenotype, fail to replicate in response to further antigenic stimulation, and express the killer cell lectin-like receptor G1 (KLRG1) and/or CD57. Physical exercise elicits a mobilization of large numbers of T lymphocytes into the bloodstream from peripheral lymphoid compartments, but the frequency of senescent cells in the mobilized population is not known. Eight male runners (age: 29 ± 9 yr; maximal O2 uptake 62 ± 6 ml·kg−1·min−1) performed an intensive treadmill-running protocol at 80% maximal O2 uptake to volitional exhaustion. Blood lymphocytes isolated before, immediately after, and 1 h after exercise were assessed for cell surface expression of KLRG1, CD57, CD28, CD45RA, CD45RO, CD62L, and lymphocyte subset markers (CD3, CD4, CD8, CD56) by flow cytometry. The percentage of all CD3+ T lymphocytes expressing KLRG1 and CD57 increased with exercise ( P < 0.01). The change in T-lymphocyte KLRG1 expression was attributed to both CD4+ and CD8 bright T cells, with the relative change being greater for the CD8 bright population ( P < 0.01). Mobilized T-lymphocyte populations expressing KLRG1 and CD57 appeared to extravasate the peripheral blood compartment after 1 h of recovery. In conclusion, T lymphocytes with a senescent phenotype are mobilized and subsequently removed from the bloodstream in response to acute high-intensity exercise. This suggests that T lymphocytes contained within the peripheral lymphoid compartments that are mobilized by exercise are likely to be at a more advanced stage of biological aging and have a reduced capacity for clonal expansion than blood-resident T cells.

Follicular lymphoma intratumoral CD4+CD25+GITR+ regulatory T cells potently suppress CD3/CD28-costimulated autologous and allogeneic CD8+CD25- and CD4+CD25- T cells

Regulatory T cells (T(R)) play a critical role in the inhibition of self-reactive immune responses and as such have been implicated in the suppression of tumor-reactive effector T cells. In this study, we demonstrate that follicular lymphoma (FL)-infiltrating CD8+ and CD4+ T cells are hyporesponsive to CD3/CD28 costimulation. We further identify a population of FL-infiltrating CD4+CD25+GITR+ T(R) that are significantly overrepresented within FL nodes (FLN) compared with that seen in normal (nonmalignant, nonlymphoid hyperplastic) or reactive (nonmalignant, lymphoid hyperplastic) nodes. These T(R) actively suppress both the proliferation of autologous nodal CD8+CD25- and CD4+CD25- T cells, as well as cytokine production (IFN-gamma, TNF-alpha and IL-2), after CD3/CD28 costimulation. Removal of these cells in vitro by CD25+ magnetic bead depletion restores both the proliferation and cytokine production of the remaining T cells, demonstrating that FLN T cell hyporesponsiveness is reversible. In addition to suppressing autologous nodal T cells, these T(R) are also capable of suppressing the proliferation of allogeneic CD8+CD25- and CD4+CD25- T cells from normal lymph nodes as well as normal donor PBL, regardless of very robust stimulation of the target cells with plate-bound anti-CD3 and anti-CD28 Abs. The allogeneic suppression is not reciprocal, as equivalent numbers of CD25+FOXP3+ cells derived from either normal lymph nodes or PBL are not capable of suppressing allogeneic CD8+CD25- and CD4+CD25- T cells, suggesting that FLN T(R) are more suppressive than those derived from nonmalignant sources. Lastly, we demonstrate that inhibition of TGF-beta signaling partially restores FLN T cell proliferation suggesting a mechanistic role for TGF-beta in FLN T(R)-mediated suppression.

Lower GrB+ CD62Lhigh CD8 TCM effector lymphocyte response to influenza virus in older adults is associated with increased CD28null CD8 T lymphocytes

Older adults who are at risk of developing influenza illness, have a low level of influenza virus-stimulated cytotoxic T lymphocyte (CTL) activity as measured by an assay of granzyme B (GrB). The purpose of this study was to determine whether aging affected memory CTL populations identified by GrB expression in influenza virus-stimulated peripheral blood mononuclear cells (PBMC). The expression and activity of GrB increased with virus stimulation over 5 days of culture. Virus-specific CD8 effector T cells with the phenotype, GrB+ CD62L(high) CD8 T(CM), were found to be the source of the early CTL response to influenza virus. Comparing the CD8 T cell response in 5-day PBMC cultures of 161 adult subjects, the response of GrB+ CD62L(high) CD8 T(CM) lymphocytes in older individuals was significantly lower than in younger adults after viral stimulation (p<0.001). The increase in the proportion of CD28(null) CD8 T cells in fresh PBMC negatively correlated with the proportion GrB+ CD62L(high) CD8 T(CM) lymphocytes in virus-stimulated PBMC. Thus, the increase in CD28(null) CD8 T cells with age may contribute to the limited CTL response to influenza vaccination and diminished protection in older adults.

IL-7/STAT5 cytokine signaling pathway is essential but insufficient for maintenance of naive CD4 T cell survival in peripheral lymphoid organs

Constitutive expression of suppressors of cytokine signaling (SOCS)1 in T lineage in vivo attenuated cytokine signaling and resulted in a dramatic reduction in the number of naive CD44(low)CD62L(high) CD4 T cells in the spleen. After adoptive transfer of thymocytes from SOCS1 transgenic mice into normal recipients, naive CD4 T cells rapidly disappeared from the spleen within 1 wk. Likewise, T cell-specific deletion of STAT5a/b in vivo resulted in a similar phenotype characterized by loss of naive CD4 T cells. Thus, STAT5-mediated signaling is crucial for promoting naive T cell survival. However, forced expression of constitutively active STAT5 failed to rescue CD4 T cells in SOCS1 transgenic mice, implying that STAT5 activation is necessary but not sufficient for naive CD4 T cell survival. Although blockade of the IL-7R, a SOCS1 target, resulted in clear inhibition of naive T cell survival, the effect occurred 3 wk after anti-IL-7R Ab treatment, but not at earlier time points. These results suggest that IL-7-mediated STAT5 activation is essential for long-term survival of naive CD4 cells after export from thymus, and that another SOCS1-sensitive cytokine is critical for short-term naive T cell survival.

Analyses of immunosenescent markers in patients with autoimmune disease

The objective of this study was to evaluate the degree of immunosenescence in patients with autoimmune disease. T cell receptor excision circles (TREC) and the percentage of CD4+CD28null T cells were studied as markers of immunosenescence in 175 patients with chronic autoimmune arthritis, other connective tissue autoimmune diseases, multiple sclerosis and 60 healthy controls. In both the rheumatoid arthritis (RA) and multiple sclerosis patient group, TREC numbers were age-inappropriately declined which points to an accelerated thymic output. Furthermore, enhanced percentages of CD4+CD28null T cells could be detected in a significant proportion of patients included in this study. These immunosenescent phenomena seemed to be present already early in the disease process. High percentages of CD4+CD28null T cells were associated with the presence of RA linked HLA DR4 alleles and with plasma reactivity to cytomegalovirus. Further analysis of CD4+CD28null T cells provided indications for a restricted T cell receptor (TCR) BV gene expression and cytoplasmic stores of various cytotoxic molecules. This study indicates that the immune system of patients with autoimmune diseases shows signs of an accelerated aging. Both genetic factors, such as HLA DR4, and environmental factors, like CMV infection, might speed up this immunosenescence and contribute in this way to disease pathogenesis.

B7-1 mediated costimulation regulates pancreatic autoimmunity

Costimulation by B7-1 and B7-2 molecules results in divergent biological effects. This is particularly striking in the NOD mouse, since the lack of B7-2 leads to complete protection from diabetes whereas the B7-1 deficiency causes exacerbation of disease. We tested the hypothesis that B7-1 costimulation suppresses pancreatic autoimmunity. We describe that the lack of B7-1 not only causes aberrant thymocyte maturation but also significantly enhances expansion, survival, and effector function of islet specific T cells in periphery. We also observed a significant reduction in the proportion of T-regulatory (T-regs) cells. Immunophenotypic analysis of T and APCs revealed a significantly lower frequency of T cells expressing the negative costimulatory receptor PD-1 in B7-1KO mice whereas the proportion of B7-H1 positive APCs was found to be significantly higher. Blocking studies in B7-1KO mice suggest that B7-H1 provides negative signals for anti islet CD4 and CD8 T-cell expansion but is differentially required for their priming. Our data demonstrate that deficiency of B7-1 mediated costimulation causes multitude of immunological defects, which involve reduction in T-regs and a concomitant enhancement of expansion, survival and effector potential of auto reactive T cells.

Effects of Specific Immunotherapy on the B7 Family of Costimulatory Molecules in Allergic Inflammation

The effect of allergen-specific immunotherapy (IT) on Ag presentation and T lymphocyte stimulation was evaluated by verifying the expression of costimulatory molecules in allergic patients. Thus, CD28 and CTLA-4, B7, and B7-H molecules on immune cells, as well as cytokine production, were analyzed in and out of the pollination period in 30 patients allergic to Betulaceae that had or had nor undergone specific IT. Results showed that IT attenuated the increase in the percentage of CD28(+)CD4 T cells and the decrease in the percentage of CTLA-4(+)CD4(+) T cells seen in untreated individuals. CD19(+)/CD80, CD19(+)/CD86(+), and CD14(+)/CD80(+) APCs were significantly augmented during pollination in unvaccinated individuals. B7-H1-expressing monocytes (CD14(+)) and B lymphocytes (CD19) as well as CD14 and CD19 B7-H1(+)/IL-10(+) APC were augmented in Betulaceae Ag-stimulated cell cultures of vaccinated patients independently of pollination, and were further increased in these individuals during pollination. As a result, the IL-10-IFN-gamma ratio in CD4(+), CD14(+), and CD19(+) cells increased in vaccinated patients, but decreased in unvaccinated individuals during pollination. These data clarify the cellular and molecular basis underlying the recent observation that peripheral expansion of IL-10-producing cells is associated with successful IT. B7-H1 could be an optimal target for IT of allergic diseases using mAbs.

Erythropoietin treatment in advanced multiple myeloma is associated with improved immunological functions: could it be beneficial in early disease?

Erythropoietin (Epo) is the main growth regulator of red blood cells, and recombinant human erythropoietin (rHuEpo) is thus used in clinical practice for the treatment of anaemia, primarily in kidney disease and cancer. rHuEpo treatment was found to be associated with prolonged survival of multiple myeloma (MM) patients. This clinical observation was then supported by studies on murine myeloma models. It thus appeared that rHuEpo had an anti-myeloma effect, causally related to an immunomodulatory function of rHuEpo. The present study investigated whether rHuEpo-treated MM patients acquire improved immunological functions. Treatment with rHuEpo, prescribed for anaemia that occurs in advanced disease, was associated with effects on a variety of immunological parameters and functions. This was expressed in an actual normalisation of the CD4:CD8 cell ratio, enhanced T cell phytohaemagglutinin-mediated activation and proliferation potential, T cell expression of the costimulatory CD28 and inhibitory CTLA-4 molecules, as well as reduced interleukin-6 serum values to normal levels. Furthermore, it was demonstrated that immunological abnormalities manifest in patients even in the early stages of MM. Our findings thus suggest that rHuEpo treatment might be effective in the early stages of MM, before anaemia develops. It is expected that this would boost the immune system, consequently achieving an anti-myeloma function; affecting disease progression and improving the prognosis.

Functional and phenotypic characterization of CD8+CD28+ and CD28- T cells in atopic individuals sensitized to Dermatophagoides pteronyssinus

BACKGROUND

CD8+ T suppressor cells may play a role in immunoregulation. Recent studies have characterized this population by the lack of the CD28 molecule. These CD8+CD28 T cells differ phenotypically and functionally from CD8 + CD28 + T cells. Little is known about CD8 + CD28 cells in atopy. Our aim was to analyze the phenotype and functional properties of CD8 + CD28T cells in atopic and non-atopic individuals.

METHODS

Peripheral blood mononuclear cells (PBMC) were obtained after density gradient centrifugation. CD8 + CD28 and CD8 + CD28 + T cells were isolated using immunomagnetic beads. Relative percentages of these cells and expression of several phenotypic markers were analyzed by flow cytometry. Proliferation was assessed by thymidine incorporation in isolated populations and in co-cultures with PBMC using Dermatophagoides pteronyssinus as stimulus. Cytokine synthesis was evaluated in culture supernatants by cytometric bead array.

RESULTS

The relative percentages of CD8+CD28 T cells and their phenotypic expression in atopic and non-atopic volunteers were not significantly different. However, CD8 + CD28 T cells showed greater proliferation than did CD8+CD28+ T cells when stimulated with D. pteronyssinus, although cytokine synthesis patterns were similar. CD8+CD28 co-cultures with PBMC showed greater proliferation than CD8+CD28+ T cell co-cultures, but cytokine synthesis patterns were not different.

CONCLUSIONS

Our data confirm phenotypic and functional differences between CD28+ and CD28 T cells, irrespective of atopic status. Purified human CD8+CD28 T cells, freshly isolated from peripheral blood, do not have suppressor properties on allergen-specific proliferation or on cytokine synthesis in PBMC.

Protective immunity to cytomegalovirus (CMV) retinitis in AIDS is associated with CMV-specific T cells that express interferon- gamma and interleukin-2 and have a CD8+ cell early maturational phenotype

To determine potential correlates of immune recovery from AIDS-related cytomegalovirus retinitis (CMVR), multiparameter flow cytometry was used to characterize CMV-specific T cells from subjects with CMVR. Individuals with active retinitis were compared with those who had been clinically immunorestored by antiretroviral therapy and had > or =2 years of ophthalmologic follow-up without anti-CMV therapy or retinitis reactivation or progression. In comparison with patients with active retinitis, immunorestored patients had higher circulating CD4(+) and CD8(+) T cells expressing interleukin-2 and interferon- gamma in response to combined CMV pp65 and IE1 peptide pool stimulation. CD4(+) T cell responses were predominantly to pp65, whereas CD8(+) T cell responses were predominantly to IE. Immunorestored patients, compared with patients with active retinitis, had increased levels of circulating CMV-specific CD8(+) T cells with "early" (CD27(+)CD28(+)CD45RA(+), CD27(+)CD28(+)CD45RA(-)) and "intermediate" (CD27(-)CD28(+)CD45RA(-)) phenotypes. Recovery from AIDS-related CMVR after the initiation of antiretroviral therapy may be mediated by CMV-specific CD4(+) and CD8(+) T cells capable of promoting antigen-specific CD8(+) T cell proliferation.

Clinical outcomes and immune reconstitution in 103 advanced AIDS patients undergoing 12-month highly active antiretroviral therapy

BACKGROUND

Highly active antiretroviral therapy (HAART) produces profound suppression of HIV replication, substantial increase in CD4(+) T cells, and partial reconstitution of the immune system. However, the numbers of subjects were small in previous Chinese studies. This study evaluated the efficacy and side effects of HAART in Chinese advanced AIDS patients.

METHODS

One hundred and three antiretroviral drug naive AIDS patients were enrolled in this study and were divided into two groups by their baseline CD4(+) count: < 100 cells/microl or > or = 100 cells/microl. Clinical, virological and immunological outcomes were monitored at baseline and at 1, 3, 6, 9 and 12 months during the course of treatment with HAART.

RESULTS

One patient died and another was lost from the follow-up. For the remaining 101 HIV/AIDS patients at the 12th month during the HAART, the plasma viral load (VL) was reduced to (3.2 +/- 0.7) lg copies/ml, the CD4(+) count increased to (168 +/- 51) cells/microl [among which the naive phenotype (CD45RA(+)CD62L(+)) increased to (49 +/- 27) cells/microl and the memory phenotype (CD45RA(-)) increased to (119 +/- 55) cells/microl], and the percentage of CD4(+)CD28(+) cells increased. At the same time, there was a significant reduction of CD8(+) T cell activation. In the 69 patients with the baseline CD4(+) count < 100 cells/microl, 37 had a VL < 50 copies/ml; while in the 34 patients with the baseline CD4(+) count > or = 100 cells/microl, 25 had a VL < 50 copies/ml, the difference between the two groups was statistically significant. The CD4(+) T cell count showed a two-phase increase during HAART and a significant positive correlation was shown between the change of CD4(+) count and plasma VL. Over 12 months of HAART, 10 patients had gastrointestinal side effects, 13 peripheral neuritis, 7 hepatic lesions, 8 hematological side effects, 8 skin rashes, 10 lipodystrophy and 1 renal calculus.

CONCLUSIONS

Immune reconstitution as well as the significantly improved clinical outcomes is observed in Chinese advanced AIDS patients after HAART. Side effects are common during HAART and require clinical attention.

Phenotypic and Functional Status of Intrahepatic T Cells in Chronic Hepatitis C

Polychromatic flow-cytometric assays were used to analyze paired intrahepatic and peripheral lymphocyte samples from 37 patients with chronic hepatitis C. Compared with peripheral cells, intrahepatic T cells were selectively enriched with CD45RO+ memory T cells but had a lower percentage of CD4+ T cells expressing the differentiation markers CD27 and CD28. The percentage of intrahepatic CD45RO+ and CD28+ T cells correlated with the degree of liver inflammation, which suggests that memory T cells at relatively early stages of differentiation are directly involved in liver inflammation. Despite their memory phenotype, intrahepatic T cells were defective in proliferation capability, produced less interferon- gamma in response to stimulation by T cell receptor, and contained less perforin but expressed higher levels of Fas and Fas ligand, compared with their counterparts in peripheral blood. The distinct characteristics of intrahepatic T cells suggest that they play an important role in the immunopathogenesis of chronic hepatitis C.

Echinococcus multilocularis metacestodes modulate cellular cytokine and chemokine release by peripheral blood mononuclear cells in alveolar echinococcosis patients

Infection with the cestode Echinococcus multilocularis causes human alveolar echinococcosis (AE), a life-threatening disease affecting primarily the liver. Despite the severity of AE, clinical symptoms often develop only many years after infection, which suggests that E. multilocularis has developed mechanisms which depress anti-parasite immune response, thus favouring immune evasion. In this study we examined the production of cytokines, chemokines and the expression of CD molecules on peripheral blood mononuclear cells (PBMC) from AE patients and healthy controls in response to E. multilocularis metacestode culture supernatant, viable E. multilocularis vesicles and E. multilocularis vesicle fluid antigen in vitro. After 48 h of co-culture, E. multilocularis metacestode culture supernatant and E. multilocularis vesicles depressed the release of the proinflammatory cytokine interleukin (IL)-12 by PBMC. This effect was dose-dependent and a suppression of tumour necrosis factor (TNF)-alpha and IL-12 was observed even when PBMC were activated with lipopolysaccharide (LPS). Comparing proinflammatory cytokine release by AE patients and controls showed that the release of IL-12 and TNF-alpha was reduced in AE patients, which was accompanied by an increased number of CD4+ CD25+ cells and a reduced release of the Th2 type chemokine CCL17 (thymus and activation regulated chemokine, TARC), suggesting an anti-inflammatory response to E. multilocularis metacestode in AE patients. Instead the production of interferon (IFN)-gamma and the expression of CD28 on CD4+ T cells were increased in PBMC from AE patients when compared to controls. This was accompanied by a higher release of the Th2-type chemokine CCL22 (macrophage derived chemokine, MDC) supporting that E. multilocularis also generates proinflammatory immune responses. These results indicate that E. multilocularis antigens modulated both regulatory and inflammatory Th1 and Th2 cytokines and chemokines. Such a mixed profile might be required for limiting parasite growth but also for reducing periparasitic tissue and organ damage in the host.

Large-scale expansion of rat CD4+ CD25+ T(reg) cells in the absence of T-cell receptor stimulation

T-cell receptor (TCR) stimulation is both central to homeostatic maintenance of CD4(+) CD25(+) regulatory T cells (T(reg) cells) in vivo and a prerequisite for the initiation of suppression by T(reg) cells, both in vivo and in vitro. However, TCR-independent stimulation of T(reg) cells, e.g. with superagonistic CD28-specific monoclonal antibodies (CD28-SA), not only expands these cells in vivo but, as we show here, also mediates large-scale expansion of rat T(reg) cells in vitro. Interestingly, CD28-SA stimulation plus interleukin (IL)-2 was even superior to conventional costimulation plus IL-2 in promoting T(reg) cell growth in vitro. Despite their highly activated phenotype suppression by T(reg) cells expanded in the absence of TCR stimulation remained fully dependent on TCR-triggering for initiation and cell contact was required to exert suppression. With regard to the regulation of suppression by CD28 stimulation we observed that neither the presence of a conventional anti-CD28 monoclonal antibody nor a CD28-SA generally rendered conventional T cells resistant to suppression by preactivated T(reg) cells. Taken together, we provide a novel protocol for long-term propagation of T(reg) cells in vitro and our data are the first to reveal a difference in the signals required for activation and expansion of T(reg) cells and those, involving the TCR, necessary for the initiation of suppression.

HIV-1 transgenic rat CD4+ T cells develop decreased CD28 responsiveness and suboptimal Lck tyrosine dephosphorylation following activation

Impaired CD4+ T cell responses, resulting in dysregulated T-helper 1 (Th1) effector and memory responses, are a common result of HIV-1 infection. These defects are often preceded by decreased expression and function of the alpha/beta T cell receptor (TCR)-CD3 complex and of co-stimulatory molecules including CD28, resulting in altered T cell proliferation, cytokine secretion and cell survival. We have previously shown that HIV Tg rats have defective development of T cell effector function and generation of specific effector/memory T cell subsets. Here we identify abnormalities in activated HIV-1 Tg rat CD4+ T cells that include decreased pY505 dephosphorylation of Lck (required for Lck activation), decreased CD28 function, reduced expression of the anti-apoptotic molecule Bcl-xL, decreased secretion of the mitogenic lympokine interleukin-2 (IL-2) and increased activation induced apoptosis. These events likely lead to defects in antigen-specific signaling and may help explain the disruption of Th1 responses and the generation of specific effector/memory subsets in transgenic CD4+ T cells.

Premature immunosenescence in rheumatoid arthritis and multiple sclerosis patients

Patients with T-cell-mediated autoimmune diseases show immune system abnormalities that resemble the typical characteristics of autoimmune dysfunction described in the elderly. In addition, the incidence of autoimmune disease increases with advancing age. To evaluate whether patients with rheumatoid arthritis (RA) and multiple sclerosis (MS) have premature immuno-senescence, we measured two indicators of aging: the number of T-cell-receptor excision circles (TRECs) and the percentage of CD4+CD28(null) T cells. We studied them in the peripheral blood mononuclear cells (PBMCs) of 60 RA patients, 32 MS patients, and 40 healthy controls (HCs). We found that TREC numbers were lower in RA and MS patients than in age-matched HCs, indicating premature thymic involution. Moreover, a subset of these patients contained age-inappropriate high frequencies of CD4+CD28(null) T cells. This study provides evidence of premature immune system senescence in both RA and MS patients. Premature aging could be a risk factor for developing autoimmune disorders in genetically predisposed individuals in a susceptible environment.

Analysis of CD28 and bcl-2 Expression on Peripheral Blood and Liver-Infiltrating Mononuclear Cells in Patients with Autoimmune Hepatitis

Because the underlying mechanism of hepatocellular damages in autoimmune hepatitis (AIH) still remains unclear, analysis of CD28 and bcl-2 molecules, which are critical for T cell activation and survival, was performed in patients with AIH. The number of CD28(+)CD4(+) peripheral blood mononuclear cells (PBMC) in corticosteroid (CS)-treated patients was comparable to normal control individuals but decreased in untreated AIH patients. In contrast, the number of CD28(+)CD8(+) PBMC was decreased in both CS-treated and untreated AIH patients. Analysis of liver-infiltrating mononuclear cells (LIMC) showed that the number of CD28(+)CD4(+) and CD28(-)CD8(+) LIMC were positively correlated with the histology activity index score. Bcl-2(+)CD4(+) LIMC were observed in the portal area of the liver and the numbers fluctuated with disease activity during the time course after CS administration. By contrast, CD8(+) LIMC were shown not to express bcl-2. Taken collectively, these results suggest that bcl-2(+)CD28(+)CD4(+) and bcl-2(-)CD28(-)CD8(+) cells may play critical and distinct roles in hepatocellular damage in AIH.

Nucleophosmin/anaplastic lymphoma kinase (NPM/ALK) oncoprotein induces the T regulatory cell phenotype by activating STAT3

The mechanisms of malignant cell transformation mediated by the oncogenic, chimeric nucleophosmin/anaplastic lymphoma kinase (NPM/ALK) tyrosine kinase remain only partially understood. Here we report that the NPM/ALK-carrying T cell lymphoma (ALK+TCL) cells secrete IL-10 and TGF-beta and express FoxP3, indicating their T regulatory (Treg) cell phenotype. The secreted IL-10 suppresses proliferation of normal immune, CD3/CD28-stimulated peripheral blood mononuclear cells and enhances viability of the ALK+TCL cells. The Treg phenotype of the affected cells is strictly dependent on NPM/ALK expression and function as demonstrated by transfection of the kinase into BaF3 cells and inhibition of its enzymatic activity and expression in ALK+TCL cells. NPM/ALK, in turn, induces the phenotype through activation of its key signal transmitter, signal transducer and activator of transcription 3 (STAT3). These findings identify a mechanism of NPM/ALK-mediated oncogenesis based on induction of the Treg phenotype of the transformed CD4(+) T cells. These results also provide an additional rationale to therapeutically target the chimeric kinase and/or STAT3 in ALK+TCL.

Modulation of CD4 + CD28 null T Lymphocytes by Tumor Necrosis Factor-α Blockade in Patients With Unstable Angina

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that favors the expansion of CD4(+)CD28null T cells, an aggressive and unusual proinflammatory lymphocyte subset frequently observed in patients with unstable angina (UA). The purpose of the present ex vivo study was to evaluate whether inflammation in patients with UA may be modulated by selective blockade of TNF-alpha.

METHODS AND RESULTS

Peripheral blood samples were collected from 17 patients with UA (Braunwald's class IIIB). CD4(+)CD28null T cells were assessed by flow cytometry and expressed as a percentage of all CD4+ T cells after 24 hours of incubation of whole blood with and without increasing doses (0.1, 1, 10, and 100 microg/mL) of infliximab, an anti-TNF-alpha monoclonal antibody. In addition, CD28 expression was assessed and expressed as mean fluorescence intensity (geometric mean of the CD28 fluorescence value on all CD4+ T cells). CD4(+)CD28null T-cell percentage decreased from a median of 6.2% (range, 1.2% to 23.9%) to 4.9% (range, 1.1% to 21.9%), 4.5% (range, 1.1% to 21.6%), and 4.1% (range, 0.4% to 21.4%) after incubation with 1, 10, and 100 microg/mL of infliximab (P for trend=0.043). Analysis of CD28 mean fluorescence intensity showed that the expression of CD28 on cell surface significantly increased after incubation with increasing doses of infliximab (P for trend=0.03).

CONCLUSIONS

The findings of this ex vivo study show that CD4(+)CD28null T-cell expansion in patients with UA may be reduced by selective TNF-alpha blockade. Further studies are warranted to evaluate the clinical benefit of CD4(+)CD28null T-cell modulation.

Naive T Cells in the Elderly: Are They Still There?

One of the most striking changes in the primary lymphoid organs during human aging is the progressive involution of the thymus. As a consequence, the rate of naïve T cell output dramatically declines with age and the peripheral T cell pool shrinks. These changes lead to increased incidence of severe infections and decreased protective effect of vaccinations in the elderly. Little is, however, known of the composition and function of the residual naïve T cell repertoire in elderly persons. To evaluate the impact of aging on the naïve T cell pool, we investigated the quantity, phenotype, function, composition, and senescence status of CD45RA(+)CD28(+) human T cells--a phenotype generally considered as naïve cells--from both young and old healthy donors. We found a significant decrease in the number of CD45RA(+)CD28(+) T cells in the elderly, whereas the proliferative response of these cells is still unimpaired. In addition to their reduced number, CD45RA(+)CD28(+) T cells from old donors display significantly shorter telomeres and have a restricted TCR repertoire in nearly all 24 Vbeta families. These findings let us conclude that naïve T cells cannot be classified with conventional markers in old age.

[Quantification and phenotypic analysis of hCMV specific CTL in peripheral blood from HLA-A2+ donors]

AIM

To optimize tetramer staining condition using HLA-A*0201 tetramer (A2-NLV tetramer) loaded with NLV peptide (pp65(495-503)) derived from structural protein pp65 of human cytomegalovirus and to investigate its application in phenotyping of specific cytotoxic T lymphocytes (CTL).

METHODS

Peripheral blood from HLA-A2(+) donors was first stained with A2-NLV tetramer/PE under different conditions and then labeled with anti-CD3-FITC and anti-CD8-APC. The stained samples were analyzed with flow cytometry to find out the optimized staining condition. Meanwhile, the phenotype and activation antigen expression were determined.

RESULTS

Tetramer staining with whole blood was superior to peripheral blood mononuclear cells. The optimized condition for tetramer staining was incubating 100 muL of whole blood with 0.3 mug of A2-NLV tetramer for 1 h at 4 degrees Celsius. Under this condition the specific staining was strong while unspecific staining of CD8(-) T cells was quite weak. Phenotypic analysis under this condition showed that the ratio of CD28 positive A2-NLV tetramer specific CTL was lower than that of nonspecific CTL, whereas the ratio of CD57 positive specific CTL was higher than that of nonspecific CTL. CD25 molecules were only expressed on the activated specific CTL.

CONCLUSION

The optimized tetramer staining condition can increase the specificity of tetramer staining and decrease unspecific binding, therefore it is applicable for phenotyping and functional analysis of antigen-specific CTL.

CD28-mediated costimulation impacts on the differentiation of DC vaccination-induced T cell responses

Costimulatory signals such as the ones elicited by CD28/B7 receptor ligation are essential for efficient T cell activation but their role in anti-tumour immune responses remains controversial. In the present study we compared the efficacy of DC vaccination-induced melanoma specific T cell responses to control the development of subcutaneous tumours and pulmonary metastases in CD28-deficient mice. Lack of CD28-mediated costimulatory signals accelerated tumour development in both model systems and also the load of pulmonary metastases was strongly increased by the end of the observation period. To scrutinize whether lack of CD28 signalling influences priming, homing or effector function of Trp-2(180-188)/K(b)-reactive T cells we investigated the characteristics of circulating and tumour infiltrating T cells. No difference in the frequency of Trp-2(180-188)/K(b)-reactive CD8+ T cells could be demonstrated among the cellular infiltrate of subcutaneous tumours after DC vaccination between both genotypes. However, the number of IFN-gamma-producing Trp-2-reactive cells was substantially lower in CD28-deficient mice and also their cytotoxicity was reduced. This suggests that CD28-mediated costimulatory signals are essential for differentiation of functional tumour-specific CD8+ T-effector cells despite having no impact on the homing of primed CD8+ T cells.

Interleukin 12 induces T-cell recruitment into the atherosclerotic plaque

CD4 T cells, through the release of cytokines as well as direct effector functions, have been implicated in promoting inflammation of the atherosclerotic plaque. Plaque-infiltrating CD4 T cells include a specialized subset of (CD4+)CD28- T cells that express a unique profile of regulatory receptors and are responsive to novel microenvironmental cues. Here we report that (CD4+)CD28- T cells, either isolated from the plaque tissue or from the blood of patients with acute coronary syndrome (ACS), spontaneously express interleukin (IL)-12 receptors, even in the absence of antigenic stimulation. (CD4+)CD28- IL-12R+ cells responded to IL-12 stimulation with the upregulation of the chemokine receptor CCR5 and the C-type lectin receptor CD161, both implicated in regulating tissue homing of effector T cells. IL-12 treatment of (CD4+)CD28- T cells enhanced their chemotaxis and transendothelial migration toward the chemokine CCL5. In vivo relevance for the role of IL-12 in regulating the recruitment of (CD4+)CD28- T cells into the atheroma was examined in human atheroma-SCID mouse chimeras. Exposure of nonstimulated (CD4+)CD28- T cells to IL-12 was sufficient to amplify T-cell accumulation within the inflamed plaque, and coadministration of anti-CCR5 antibodies blocked T-cell recruitment into the plaque. Thus, (CD4+)CD28- T cells functionally resemble NK cells, which have proinflammatory activity even in the unprimed state and respond to any IL-12-inducing host infection with a shift in tissue trafficking and accrual in inflammatory lesions.

Foxp3 Expressing CD4+ CD25+ and CD8+CD28− T Regulatory Cells in the Peripheral Blood of Patients with Lung Cancer and Pleural Mesothelioma

The role of T regulatory (Treg) cells in human cancer has not yet been clarified. We assessed the presence and function of CD4+ and CD8+ Treg cell subsets in the peripheral blood of patients with lung cancer (LC) and pleural mesothelioma (PM). We found a low but significant increase in the number of CD4+ T cells with phenotype and functional features of Treg cells in LC patients compared to normal healthy controls (NHC). Furthermore, total CD4+ T cells from LC patients proliferated less than cells from controls, suggesting that the increase in the CD4+ Treg cell pool has functional importance. LC patients also showed an expansion of the CD8+CD28- T cell subset and these cells expressed Foxp3 mRNA, as recently observed in alloantigen-specific CD8+CD28- T suppressor cells. No variation of peripheral Treg cell subsets was found in patients with PM, a disease with a predominantly localized nature. However, the lack of correlation between cancer stage and the number or the function of peripheral Treg cells in LC patients refuted the hypothesis that these cells are involved in tumor spreading. A possible involvement of the peripheral Treg cell pool in cancer development and/or in inducing systemic immunosuppression in LC patients can be hypothesized.

Regulation of ILT3 gene expression by processing of precursor transcripts in human endothelial cells

Immunoglobulin-like transcript (ILT)-3 is a transmembrane receptor, which belongs to the immunoglobulin superfamily. In previous studies, we showed that allospecific CD8+CD28- T suppressor cells (Ts) induce the expression of ILT3 in human endothelial cells (EC) rendering them tolerogenic. Using a polymerase chain reaction (PCR)-based approach, we now demonstrate by cell fractionation and sequencing studies that ILT3 precursor RNA is expressed and retained in nuclei of resting EC. Ts interaction with EC or exposure of EC to interleukin-10 (IL-10) and interferon alpha (IFN-alpha) triggers processing of ILT3 pre-mRNA. Western blot analysis showed that the expression of the mature ILT3 transcript is accompanied by production of ILT3 protein.

Increased activation and expansion of a CD57+ subset within peripheral CD8+ T lymphocytes in Mycobacterium tuberculosis-infected patients

BACKGROUND

Mycobacterium tuberculosis-specific CD8+ and CD4+ T lymphocyte responses restrict the spread of extracellular pathogens by limiting M.tuberculosis replication. Alterations in cytolytic function, inappropriate maturation/differentiation, and limited proliferation could reduce their ability to control M.tuberculosis replication.

METHODS

In an attempt to further characterize the immune responses during M.tuberculosis infection, we enumerated gamma-delta and alpha-beta receptor-bearing T cells expressing CD8 or CD4 phenotype and analyzed the differentiation phenotypes of CD8+ and CD4+ T lymphocyte subpopulations in 47 cases (23 new cases and 24 multidrug resistant patients) and 20 control subjects, using flowcytometry.

RESULTS

We found that the CD4/CD8 ratio was significantly lower in newly-diagnosed M.tuberculosis patients compared to multidrug resistant and control subjects (P < 0.003). Also, we found that a large proportion of CD8+ T lymphocytes in newly-diagnosed patients was defined by increased surface expression of CD57 as compared to the two other settings (P < 0.002). This increase was more profound in patients with an inverted CD4/CD8 ratio. Analysis of the late activation antigen revealed that this was predominantly HLA-DR+ (P < 0.003). No significant changes were observed in the percentages of CD8+CD57+ T cells between the different settings. Moreover, the co-stimulatory molecule CD28+ tended to be underexpressed by CD8+ T cells in multidrug resistant patients when compared to newly-diagnosed subjects (P < 0.002), but not to the control subjects. In contrast, the frequency of CD28+ marker on CD4+ T cells was higher in the setting of multidrug resistant compared with those of new cases (P < 0.0001). No significant changes were observed in percentages of gamma-delta receptor-bearing T cells between different groups.

CONCLUSION

We suggest that the increase in the proportion of CD57+ within CD8+ T cells in newly-diagnosed patients results from M.tuberculosis antigenic stimulation, which is a hallmark of many infections and that the protracted accumulation of CD57+ T lymphocytes might reflect an end-stage differentiation phenotype.

Age-related changes in cell surface and senescence markers in the spleen of DBA/2 mice: a flow cytometric analysis

In murine studies of immune senescence cell preparations from whole organs, e.g. splenocytes, are frequently reported. However, age-related changes in spleen cell types have been poorly defined throughout the spectrum of adult age or across murine strains. The aim of this study was to use flow cytometry to more fully characterize cell types within the spleen of DBA/2 mice, a strain available from the National Institute of Aging (NIA), across the entire adult age spectrum. In advanced age, B cells comprise a greater percentage of the total splenocyte population, and there is a decline in the percentage of gammadelta+T cells in the spleen. The percentage of memory CD4+T cells increases in middle age with a corresponding decrease in the percentage of naïve CD4+T cells. Expression of the co-stimulatory molecule CD28 on splenic CD4+ and CD8+T cells increases with age, but CD28 expression on peripheral blood T cells does not change. The senescence marker p16INK4a increases in B cells and CD8+T cells within the spleen and can be measured by flow cytometry.

Phenotypically and Functionally Distinct CD8+ Lymphocyte Populations in Long-Term Drug-Free Tolerance and Chronic Rejection in Human Kidney Graft Recipients

A substantial proportion of long-term kidney graft recipients, including those with a stable renal function in the absence of immunosuppressive therapy, present a skewed T cell receptor (TCR) Vbeta chain usage, essentially in the CD8+ subset. This study analyzed in more detail phenotypical and functional alterations of CD8+ lymphocytes in drug-free tolerant patients (DF-Tol) compared with recipients with chronic rejection (CR). Phenotyping revealed a significant increase in central memory and a decrease in effector CD8+ lymphocytes in DF-Tol versus CR. The expression of CD28+ and CD27+ on these effector cells was significantly decreased in CR. These profiles were stable over time and independent of treatment. Functionally, the CD8+CD28- lymphocytes were less sensitive to apoptosis than their CD8+CD28+ counterparts, without differences in polyclonal proliferation. The CD8+CD28- cells did not express GITR and FoxP3 but were characterized by high levels of preformed perforin and granzyme A, pointing toward a cytotoxic rather than a suppressor function. CD8+CD28- lymphocytes did not show antigen-specific degranulation when co-cultured with targets that bear donor HLA class I antigens, suggesting that the cytotoxicity is directed either to other determinants of the graft or to nongraft epitopes. Of interest, CD8+ cells from DF-Tol displayed the same profile as healthy individuals, indicating an increase in CD8+CD28- effector lymphocytes in CR rather than a decrease in DF-Tol. CD8+ lymphocytes from stable kidney recipients under conventional maintenance immunosuppression displayed a mixed profile, independent of treatment and time of sampling. Taken collectively, these data show a strong cytotoxicity-associated CD8+CD28- signature in CR and suggest a suppression of pathologic cytotoxicity in DF-Tol. Further prospective studies should assess whether serial CD8+ phenotyping may help to identify patients who are at risk for CR when immunosuppression is tapered.

Blockade of Both CD28/B7 and OX40/OX40L Co-Stimulatory Signal Pathways Prolongs the Survival of Islet Xenografts

CTLA4Ig, a recombinant fusion protein composed of the extracellular domain of human CTLA4 and the constant region of human IgG1, inhibits the interaction of CD28/B7 pathway by binding the B7 molecule. OX40Ig, a recombinant fusion protein composed of the extracellular domain of human OX40 and the constant region of human IgG1, abrogates the interaction of OX40/OX40L pathway by binding the OX40L on APCs. So blockade of CD28/B7 or OX40/OX40L co-stimulatory pathways alone in mice with CTLA4Ig or OX40Ig can result in finitely prolonging the survival of islet grafts (43.2 +/- 4.81 and 67.7 +/- 7.74 days, respectively). In this study, a novel replication-defective adenovirus containing both of the CTLA4Ig and OX40Ig genes, AdCTLA4Ig-IRES-OX40Ig, was constructed by homologous recombination and injected into the streptozocin-rendered diabetic BalB/c mouse recipients (H-2d) through the tail vein, at the same day, the freshly isolated islets from Lewis rats (RT-1) were transplanted under the left kidney capsule of the recipients. The results showed that the mean survival time of the islet xenografts in the AdCTLA4Ig-IRES-OX40Ig-treated diabetic mice was significantly prolonged (100.3 +/- 14.94 days), while those in the untreated or AdEGFP-treated mice were rejected in normal fashion (6.7 +/- 0.94 and 7.0 +/- 1.0 days, respectively). In conclusion, utilizing AdCTLA4Ig-IRES-OX40Ig in vivo which can simultaneously express CTLA4Ig and OX40Ig proteins can improve the survival of Lewis-->BalB/c islet xenografts.

Human CD4+T Cells Are Predominantly Distributed among Six Phenotypically and Functionally Distinct Subsets

Human T cells are heterogeneous, varying in terms of their phenotype, functional capabilities, and history of Ag encounter. The derivation of a functionally relevant model for classifying CD4+ T cells has been hampered by limitations on the numbers of parameters that may be measured using classical four-color flow cytometry. In this study we have taken advantage of the introduction of reagents for five-color flow cytometry to develop a detailed, functionally meaningful scheme for classifying human CD4+ T cells. We show that CD4+ T cells are predominantly distributed among six of eight possible compartments, identified by the expression of CCR7, CD45RA, and CD28. We demonstrate novel phenotypic and functional correlates that justify the choice of these three molecules to define CD4+ T cell compartments. We note that CD4+ T cells with different Ag specificities are distributed differently among the six described subsets. On the basis of these results, we propose a cross-sectional model for classification of peripheral CD4+ T cells. Knowledge of where T cells lie on this model informs about their functional capacity and can reflect their history of Ag exposure.

Phenotyping of lymphocytes expressing regulatory and effector markers in infiltrating ductal carcinoma of the breast

Dysfunction of the host immune system in cancer patients can be due to a number of reasons including suppression of tumour associated antigen reactive lymphocytes by regulatory T (Treg) cells. In this study, we used flow cytometry to determine the phenotype and relative abundance of the tumour infiltrating lymphocytes (TILs) from 47 enzymatically dissociated tumour specimens from patients with infiltrating ductal carcinoma (IDC) of the breast. The expression of both effector and regulatory markers on the TILs were determined by using a panel of monoclonal antibodies. Analysis revealed CD8(+) T cells (23.4+/-2.1%) were predominant in TILs, followed by CD4(+) T cells (12.6+/-1.7%) and CD56(+) natural killer cells (6.4+/-0.7%). The CD4(+)/CD8(+) ratio was 0.8+/-0.9%. Of the CD8(+) cells, there was a higher number (68.4+/-3.5%) that expressed the effector phenotype, namely, CD8(+)CD28(+) and about 46% of this subset expressed the activation marker, CD25. Thus, a lower number of infiltrating CD8(+) T cells (31.6+/-2.8%) expressed the marker for the suppressor phenotype, CD8(+)CD28(-). Of the CD4(+) T cells, 59.6+/-3.9% expressed the marker for the regulatory phenotype, CD4(+)CD25(+). About 43.6+/-3.8% CD4(+)CD25(+) subset co-expressed both the CD152 and FOXP3, the Treg-associated molecules. A positive correlation was found between the presence of CD4(+)CD25(+) subset and age (> or =50 years old) (r=0.51; p=0.045). However, no significant correlation between tumour stage and CD4(+)CD25(+) T cells was found. In addition, we also found that the CD4(+)CD25(-) subset correlated with the expression of the nuclear oestrogen receptor (ER)-alpha in the tumour cells (r=0.45; p=0.040). In conclusion, we detected the presence of cells expressing the markers for Tregs (CD4(+)CD25(+)) and suppressor (CD8(+)CD28(-)) in the tumour microenvironment. This is the first report of the relative abundance of Treg co-expressing CD152 and FOXP3 in breast carcinoma.

Primary sooty mangabey simian immunodeficiency virus and human immunodeficiency virus type 2 nef alleles modulate cell surface expression of various human receptors and enhance viral infectivity and replication

The nef gene of the pathogenic simian immunodeficiency virus (SIV) mac239 clone has been well characterized. Little is known, however, about the function of nef alleles derived from naturally SIVsm-infected sooty mangabeys (Cercocebus atys) and from human immunodeficiency virus type 2 (HIV-2)-infected individuals. Addressing this, we demonstrate that, similarly to the SIVmac239 nef, primary SIVsm and HIV-2 nef alleles down-modulate cell surface expression of human CD4, CD28, CD3, and class I or II major histocompatibility complex (MHC-I or MHC-II, respectively) molecules, up-regulate surface expression of the invariant chain (Ii) associated with immature MHC-II, inhibit early T-cell activation events, and enhance virion infectivity. Both also stimulate viral replication, although HIV-2 nef alleles were less active in this assay than SIVsm nef alleles. Mutational analysis showed that a dileucine-based sorting motif in the C-proximal loop of SIV or HIV-2 Nef is critical for its effects on CD4, CD28, and Ii but dispensable for down-regulation of CD3, MHC-I, and MHC-II. The C terminus of SIV and HIV-2 Nef was exclusively required for down-modulation of MHC-I, further demonstrating that analogous functions are mediated by different domains in Nef proteins derived from different groups of primate lentiviruses. Our results demonstrate that none of the eight Nef functions investigated had been newly acquired after cross-species transmission of SIVsm from naturally infected mangabeys to humans or macaques. Notably, HIV-2 and SIVsm nef alleles efficiently down-modulate CD3 and C28 surface expression and inhibit T-cell activation more efficiently than HIV-1 nef alleles. These differences in Nef function might contribute to the relatively low levels of immune activation observed in HIV-2-infected human individuals.