Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus

Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25^+/highCD127^Ø/lowFoxP3⁺, and effector T cells were defined as CD25⁺CD127⁺FoxP3^Ø. The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4⁺TREG and CD28⁺TREG cells and an increased frequency of CD40L⁺TREG cells. There was a decrease in the TREG/effector-T ratio for GITR⁺, HLA-DR⁺, OX40⁺, and CD45RO⁺ cells, and an increased ratio of TREG/effector-T CD40L⁺ cells in patients with SLE. In addition, CD40L⁺TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease.

Peripheral blood telomere content is greater in patients with endometriosis than in controls

The etiology of endometriosis remains poorly understood but circulating stem cells may contribute. Telomeres shorten with cell divisions and age. Stem cells attempt to compensate for telomere attrition through the action of telomerase. Since circulating stem cells may contribute to endometriosis, we compared telomere content in lymphocytes of patients with and without endometriosis.

METHODS

Observational study comparing peripheral lymphocytes telomere content, measured by quantitative polymerase chain reaction, in patients with (n = 86) and without endometriosis (n = 21).

FINDINGS

Patients with endometriosis had longer telomeres than that of matched, endometriosis-free controls (telomere to single copy gene ratio [T/S ratio] of 1.62 vs 1.34, respectively, P = .00002). Patients with endometriosis were 8.1-fold more likely to have long telomeres. (odds ratio = 8.1, 95% confidence interval: 1.28-51.57, P = .0264).

INTERPRETATION

Longer telomeres could be consistent with a stem cell origin of endometriosis.

HCV viremia drives an increment of CD86 expression by myeloid dendritic cells

The host immune response, including innate and adaptive immunity, plays a critical role in determining the outcome of viral infection. Nevertheless, little is known about the exact reasons for the failure of the host immune system in controlling hepatitis C virus (HCV) infection. Impairment of dendritic cells (DCs) function is probably one of the mechanisms responsible for immune evasion of HCV. In this study, the frequency and phenotype of DCs subsets were analyzed in three groups: HCV-infected individuals who developed viral persistence (1), HCV-infected individuals who spontaneously cleared the virus (2) and HCV-seronegative uninfected subjects (3). The results showed that the frequency of DCs subsets was not statistically significant between groups. Plasmacytoid DCs circulating exhibited an immature phenotype characterized by low expression of CD86. On the other hand, CD86 expression in myeloid DCs was significantly higher in chronic infected individuals compared to healthy controls (P=0.037). A positive correlation was observed between CD86(+) myeloid DC (mDC) and HCV viral load (r=0.4121, P=0.0263). These results suggest that HCV did not have an inhibitory effect on mDC maturation and the HCV viremia drives the increase of CD86 expression in mDC. The regulation of DCs maturation and migration lies at the level of intracellular signaling. HCV can activate or block intracellular signaling pathways and alter DC function. In conclusion, the present study suggests that imbalance of DC maturation by the virus represents a mechanism of evasion of the immune system despite the fact that HCV viremia appears to exert a "stimulatory" effect on cell-surface immune phenotype.

Chemokines in the pathogenesis of endometriosis and infertility

Endometriosis is a chronic benign disease that affects women of reproductive age causing abdominal pain and infertility. Its pathogenesis remains obscure despite all the research conducted over the past 100 years. However, there is a consensus among the specialists that the basis of its pathophysiology would be multifactorial. Many publications have demonstrated that chemokines are somehow associated with the development of endometriosis and infertility. In this study, we reviewed all PubMed literature using MeSH terms "chemokines" and "endometriosis" as well as "chemokines" and "female infertility" to establish what we know and what we do not yet know about this relationship.

Lower numbers of circulating Natural Killer T (NK T) cells in individuals with human T lymphotropic virus type 1 (HTLV-1) associated neurological disease

Human T lymphotropic virus type 1 (HTLV-1) infects 10-20 million people worldwide. The majority of infected individuals are asymptomatic; however, approximately 3% develop the debilitating neurological disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). There is also currently no cure, vaccine or effective therapy for HTLV-1 infection, and the mechanisms for progression to HAM/TSP remain unclear. NK T cells are an immunoregulatory T cell subset whose frequencies and effector functions are associated critically with immunity against infectious diseases. We hypothesized that NK T cells are associated with HAM/TSP progression. We measured NK T cell frequencies and absolute numbers in individuals with HAM/TSP infection from two cohorts on two continents: São Paulo, Brazil and San Francisco, CA, USA, and found significantly lower levels when compared with healthy subjects and/or asymptomatic carriers. Also, the circulating NK T cell compartment in HAM/TSP subjects is comprised of significantly more CD4(+) and fewer CD8(+) cells than healthy controls. These findings suggest that lower numbers of circulating NK T cells and enrichment of the CD4(+) NK T subset are associated with HTLV-1 disease progression.

Antiretroviral drug therapy alters the profile of human immunodeficiency virus type 1-specific T-cell responses and shifts the immunodominant cytotoxic T-lymphocyte response from Gag to Pol

Antiretroviral drug therapy and cytotoxic T lymphocytes (CTL) both exert selective pressures on human immunodeficiency virus type 1, which influence viral evolution. Compared to chronically infected, antiretroviral-untreated patients, most chronically infected, treated patients with detectable viremia lack a cellular immune response against the Gag 77-85(SL9) epitope but show a new immunodominant response against an epitope in protease PR 76-84. Hence, mutations induced by antiretroviral therapy likely alter the profile of epitopes presented to T cells and thus the direction of the response. The consequences of dual pressures from treatment and CTL need to be considered in monitoring of drug therapy.

Interferon-gamma and tumour necrosis factor-alpha production by CD4+ T and CD8+ T lymphocytes in AIDS patients with tuberculosis

Tuberculosis (TB) is usually more severe in HIV-infected patients, and the immune derangement found in co-infected patients may differ from that in each isolated disease. Following mitogen stimulation of peripheral blood mononuclear cells (PBMC), interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha production was evaluated in T cells by flow cytometry, and in culture supernatants by enzyme-linked immunosorbent assay (ELISA) in 33 individuals: 11 AIDS patients with tuberculosis, six asymptomatic HIV-1-infected patients, eight patients with tuberculosis and eight healthy controls. The proportion of CD4+ T lymphocytes expressing IFN-gamma did not differ between the groups, whereas a trend towards increased proportions of TNF-alpha-expression in CD4+ T cells was observed in the TB compared to the HIV group, while intermediate values were observed in co-infected patients. Detection of IFN-gamma and TNF-alpha in CD8+ T lymphocytes was higher in TB than in HIV individuals. Co-infected patients presented intermediate values for IFN-gamma, while TNF-alpha detection was similar to that in HIV mono-infection. In conclusion, the proportion of T cells expressing IFN-gamma was relatively preserved in co-infected patients compared to TB patients, while the percentage of T cells expressing TNF-alpha was decreased, mainly in CD8+ T lymphocytes. However, the marked reduction in T lymphocyte numbers in co-infected patients led to a striking reduction of both cytokines in PBMC supernatants, a finding that is consistent with the impaired response to Mycobacterium tuberculosis.

Leptospira interrogans activation of peripheral blood monocyte glycolipoprotein demonstrated in whole blood by the release of IL-6

Glycolipoprotein (GLP) from pathogenic serovars of Leptospira has been implicated in the pathogenesis of leptospirosis by its presence in tissues of experimental animals with leptospirosis, the inhibition of the Na,K-ATPase pump activity, and induced production of cytokines. The aims of the present study were to investigate the induction of IL-6 by GLP in peripheral blood mononuclear cells (PBMC) and to demonstrate monocyte stimulation at the cellular level in whole blood from healthy volunteers. PBMC were stimulated with increasing concentrations (5 to 2500 ng/ml) of GLP extracted from the pathogenic L. interrogans serovar Copenhageni, lipopolysaccharide (positive control) or medium (negative control), and supernatants were collected after 6, 20/24, and 48 h, and kept at -80 degrees C until use. Whole blood was diluted 1:1 in RPMI medium and cultivated for 6 h, with medium, GLP and lipopolysaccharide as described above. Monensin was added after the first hour of culture. Supernatant cytokine levels from PBMC were measured by ELISA and intracellular IL-6 was detected in monocytes in whole blood cultures by flow-cytometry. Monocytes were identified in whole blood on the basis of forward versus side scatter parameters and positive reactions with CD45 and CD14 antibodies. GLP ( > or = 50 ng/ml)-induced IL-6 levels in supernatants were detected after 6-h incubation, reaching a peak after 20/24 h. The percentage of monocytes staining for IL-6 increased with increasing GLP concentration. Thus, our findings show a GLP-induced cellular activation by demonstrating the ability of GLP to induce IL-6 and the occurrence of monocyte activation in whole blood at the cellular level.

An imbalance of naive and memory/effector subsets and altered expression of CD38 on T lymphocytes in two girls with hyper-IgM syndrome

In this report we evaluated CD4(+) T, CD8(+) T and natural killer (NK) cell counts, the levels of naive/memory subsets within the CD4(+) T lymphocyte population, expression of CD38 on T lymphocytes, and CD4(+) and CD8(+) T cell cytokine production in two girls with hyper-IgM (HIM) syndrome. Both girls developed recurrent infections early in infancy, presenting a wide spectrum of clinical manifestations, with a strikingly different disease severity between them. CD4(+) T cell counts were low in both children (patient 1: 214 cells/mm(3) and patient 2: 392 cells/mm(3)), and the CD4/CD8 T cell ratio was 0.4 for patient 1, the patient with the more severe disease, and 1.4 for patient 2. NK cell numbers were low in patient 1 (60 cells/mm(3)) and borderline (286 cells/mm(3)) with regard to normal levels in patient 2. An imbalance of naive and memory/effector cell subsets was found in both girls, with the percentage of CD45RA(+) 27(+) (naive) CD4(+) T lymphocytes being 5.8 and 12.4 for patients 1 and 2, respectively. Expression of CD38 on the surface of T lymphocytes was low in patient 1. Detection of intracellular interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha in CD4(+) and CD8(+) T lymphocytes upon PMA-Io stimulus was preserved in both children. In conclusion, we found low numbers of CD4(+) T lymphocytes and a dramatic redistribution of naive and memory/effector CD4(+) T lymphocytes in two girls with non-X-linked HIM syndrome. Furthermore, we found low expression of CD38 on T lymphocytes and low numbers of NK cells in the patient with the more severe disease, indicating a possible role for these cells in the pathogenesis of this immunodeficiency.

Different kinetics in anti-cytomegalovirus immunity reconstitution evaluated by lymphocyte proliferation and IFN-gamma production in allogeneic and autologous bone marrow transplantation

Allogeneic bone marrow transplantation (ALLOBMT) is associated with an increased risk of cytomegalovirus (CMV) morbidity compared to autologous BMT (AUTOBMT). To investigate this, we evaluated AUTOBMT and ALLOBMT patients regarding anti-CMV immune reconstitution at 1 and 4 months after BMT and on the day after first CMV antigenemia detection. Intermittent ganciclovir preemptive therapy was prompted by antigenemia of >or=2 cells. One month after transplant, AUTOBMT recipients already displayed larger CD8+ T cell numbers than ALLOBMT recipients, but comparably small CD4+ T cell numbers. Most AUTOBMT patients had positive CMV antigen (CMV-Ag)-induced lymphoproliferation (86%) and IFN-gamma secretion (86%), whereas this was infrequently seen in ALLOBMT patients (20 and 10%, respectively). This early AUTOBMT immune reconstitution was associated with a lower frequency of CMV reactivation up to +4 months in AUTOBMT (21%) than ALLOBMT patients (91%). At +4 months, most ALLOBMT recipients had also recovered CMV-Ag immune responses. At first antigenemia detection, all 3 AUTOBMT recipients already displayed anti-CMV immune functions and 2 cleared the infection without therapy, whereas of the 10 ALLOBMT recipients only 1 had positive lymphoproliferation. In the latter group, none had IFN-gamma secretion or cleared the infection without therapy. Thus, differences in anti-CMV immune reconstitution may help to explain the contrasting rates of CMV morbidity between ALLOBMT and AUTOBMT patients.

Immunophenotypic characterization of peripheral T lymphocytes in Mycobacterium tuberculosis infection and disease

The cellular immune response probably plays a pivotal role in determining the clinical outcome after exposure to Mycobacterium tuberculosis. We used multi-parameter flow-cytometry to evaluate the distribution of T-lymphocyte subsets during infection and disease caused by M. tuberculosis. Samples were obtained from 71 volunteers to identify the T CD4+ and CD8+ lymphocyte numbers, and the activation plus memory/naïve phenotypes, as defined by CD38, HLA-DR, CD45RA and CD27 markers. Subjects were divided into 18 healthy volunteers without detectable reaction to purified protein derivative (PPD-), 18 health care workers with a recent conversion to PPD, 20 patients with active pulmonary tuberculosis (TBC) and 15 patients with treated TBC at 6 months of therapy. By multiple-comparison analyses, the T CD4+ lymphocyte number of the TBC group was lower than the PPD- group (P < 0.05). This difference was apparently lost after treatment. The higher and the lower number of naïve T CD4+ cells was observed in the PPD- and TBC group, respectively. CD8+ T lymphocytes were also statistically different among the four groups (P = 0.0002), lower in the TBC group (P < 0.05). CD8+ T lymphocyte activation was evaluated by the CD38 and HLA-DR surface expression. The percentage distribution of these markers was statistically different between the four groups (P = 0.0055). TBC patients had a higher percentage of CD38+ cells and mean fluorescence index, suggesting an overall increase of cell activation. These results suggest that peripheral T lymphocytes reflect cellular activation during TBC, along with possible redistribution of naïve, memory/effector and late differentiated memory/effector phenotypes in the peripheral blood after infection and disease caused by M. tuberculosis.

Pathogenetic aspects of sepsis and possible targets for adjunctive therapy

The outcome of patients with sepsis arises from multiple factors affecting both the host and the invading microorganisms. Age, presence of underlying disease, source of infection and some specific etiological agents have been related to prognosis. Appropriateness of antimicrobial therapy, considering the in vitro susceptibility tests for the infecting bacteria, has been strongly associated with the outcome. Therefore even after the cascade of sepsis has been triggered, the control of bacteria growth is still fundamental for the outcome of the infection. This is a major distinction point from experimental studies in which whole killed bacteria and their products are used as model of sepsis. However, even within the setting of adequate antimicrobial use, patients still die of sepsis. Thus, strategies focusing on further therapy targets are an important area of interest for basic and clinical research. Although such adjunctive sepsis therapy has failed to achieve consistent better survival rates so far, nevertheless, it improved our understanding of the pathophysiological events seen in sepsis that the possibility that a new and effective treatment may arise has been warmly considered. In this paper we aim to review some aspects of the pathogenesis of sepsis, focusing on recent advances and on possible targets for adjunctive therapy. Published clinical trials and experimental data supporting such trials are commented on.

Evaluation of canarypox-induced CD8+ responses following immunization by measuring the effector population IFNγ production

CD8(+) cytolytic activity is traditionally measured by detecting the release of 51Cr after incubation of effector cells with HLA-matched, infected, radiolabeled targets. An alternative method to detect CD8+ activity is to measure the production of intracellular interferon gamma (IFNgamma) after antigen-specific stimulation, either by ELISPOT or by flow cytometry. Studies were performed in 19 volunteers enrolled in a phase 1 trial of candidate canarypox HIV-1 vaccines that encoded multiple HIV-1 genes. The vaccines including vCP205 (Env, Gag, and protease), vCP1433 (Env, Gag, protease, and CTL epitope-rich regions of pol and nef) and vCP1452 (equivalent to vCP1433 with additional immunomodulatory genes of vaccinia). PBMCs were stimulated in vitro with vaccinia constructs encoding env and gag or a lacZ control, and the effectors were cultured for 12-14 days. EBV-transformed B cell lines were infected overnight with the vaccinia vectors, and then incubated with the effector cells for 4 h in the presence of monensin. CD8(+) gene-specific activity was determined as a percentage of IFNgamma cells in the CD3(+)CD8(+)CD45RO(+) gate after subtracting both the isotype control and the lacZ control stimulation. CD4 memory IFNgamma production was simultaneously determined in the CD3(+)CD8(-)CD45RO(+) gate. Using these techniques in blinded studies, we found that CD8(+) IFNgamma activity could be measured in the majority of volunteers given four immunizations. Specifically, the responses to the gag gene were control -- 0/2; vCP205 -- 2/4; vCP1433 -- 5/6; vCP1452 -- 4/7. Most of the positive responses were detected after the fourth immunization. Flow cytometric techniques hold promise as a surrogate measure of CTL and for ease of phenotyping of the effector population.

QS-21 promotes an adjuvant effect allowing for reduced antigen dose during HIV-1 envelope subunit immunization in humans

Three separate studies were undertaken in HIV-1 uninfected persons to determine if the adjuvant QS-21 improves the magnitude or kinetics of immune responses induced by recombinant soluble gp120 HIV-1(MN) protein (rsgp120) immunization. The QS-21 was administered at two doses (50 and 100 microg), either alone or in combination with aluminum hydroxide (600 microg). At the highest doses of rsgp120 (100, 300, and 600 microg), QS-21 exerted no significant effect on either binding or neutralizing antibody titers. Antibody binding and neutralizing responses fell dramatically when rsgp120, formulated with alum alone, was given at low doses (3 and 30 microg). In contrast, antibody responses similar in titer to those in the high dose antigen groups were induced with the low dose rsgp120 formulated with QS-21. In addition, the lymphocyte proliferation and delayed type hypersensitivity skin testing were superior in the QS-21 recipients compared with the alum recipients at the low antigen doses. Moderate to severe pain was observed in majority of the volunteers receiving QS-21 formulations, and vasovagal episodes and hypertension were not infrequent. Thus, the use of QS-21 may provide a means to reduce the dose of a soluble protein immunogen.

Effects of interleukin-15 on in vitro human T cell proliferation and activation

Interleukin-15 (IL-15) has been reported to have many activities on T cell populations, including a potential role in improving antigen-specific proliferation in HIV-1 disease. We tested this response in healthy adults by studying the response of T cell populations after stimulation with medium, tetanus, cytomegalovirus (CMV) antigens in cultures from 21 volunteers. IL-15 caused a dose-dependent increase in medium and antigen-induced proliferation. The expansion was due to CD8>natural killer (NK)>CD4 lymphocytes and memory > naive cells. The IL-15-stimulated CD8 cells had increased levels of the activation markers CD69 and DR. The published CMV-induced expression of CD57 on CD8+ cells was increased in CMV seronegative and seropositive subjects by IL-15. IL-15 appears to be a stimulator of T cell populations in healthy adults and may be useful in settings to enhance nonspecific NK activity or antigen-specific CD8 activity.

Primary isolate neutralization by HIV type 1-infected patient sera in the era of highly active antiretroviral therapy

Sera from highly selected HIV-1-positive patients are known to have the ability to neutralize a diverse array of primary isolates of HIV-1. The human osteosarcoma cell line that expresses CD4 and chemokine receptors (GHOST cells) was adapted to study HIV-1 neutralization in 37 HIV-1-infected individuals who were selected because of slow disease progression or nonprogression. Many of these individuals were receiving combination drug therapy. Molecularly cloned HIV-1 JR-FL and NL4-3 viruses were used as prototypes to define assay conditions. Sera were then tested at a 1:40 dilution against six additional primary isolates, three of which utilized CCR5 and three of which used both CCR5 and CXCR4. The assay was highly reproducible and independent of viral input titer, with a readout at 48 hr equivalent to that at later time points. As previously reported, neutralization sensitivity was entirely independent of coreceptor usage. Only a few sera from slow progressors were able to neutralize a broad array of primary isolates at a 1:40 dilution, and the best clinical predictor of broadly neutralizing antibody for primary isolates was the present use of antiretroviral agents. In further studies it was found that purified antibody accounted for the majority of the measured neutralization. However, experiments with exogenous addition of antiviral agents showed that the use of nucleosides also greatly contributed to the measured neutralization in some patients. Measurement of neutralization of HIV-1 primary isolates by sera from patients receiving antiretroviral therapy must be carried out with some caution.

Genealogical evidence for positive selection in the nef gene of HIV-1

The pattern and process of evolution in the nef gene of HIV-1 was analyzed within and among patients. Using a maximum likelihood method that allows for variable intensity of selection pressure among codons, strong positive selection was detected in a hemophiliac patient over 30 mo of infection. By reconstructing the process of allele substitution in this patient using parsimony, the synapomorphic amino acid changes separating each time point were found to have high probabilities of being under positive selection, with selective coefficients of at least 3.6%. Positive selection was also detected among 39 nef sequences from HIV-1 subtype B. In contrast, multiple pairwise comparisons of nonsynonymous and synonymous substitution rates provided no good evidence for positive selection and sliding window analyses failed to detect most positively selected sites. These findings demonstrate that positive selection is an important determinant of nef gene evolution and that genealogy-based methods outperform pairwise methods in the detection of adaptive evolution. Mapping the locations of positively selected sites may also be of use in identifying targets of the immune response and hence aid vaccine design.

Production of influenza-stimulated tumor necrosis factor-alpha by monocytes following acute influenza infection in humans

Tumor necrosis factor-alpha (TNF-alpha) is often measured in the serum or plasma of patients with severe infections, and marked elevation correlates with poor outcome. The relationship of TNF-alpha to protection from disease is frequently not observed because prospective studies of infectious agents are difficult to perform. We took advantage of a human antiviral influenza challenge study to correlate TNF-alpha production with seroconversion and symptom development. TNF-alpha production was measured by ELISA in the plasma compartment or was measured by intracellular production at the single cell level in the monocyte gated population. Monocyte TNF-alpha was associated with asymptomatic seroconversion, whereas there was no change in the plasma at the times measured. Measurement of TNF-alpha at the single cell level by flow cytometry may allow for better differentiation of the protective role of this cytokine in future studies.

Cytomegalovirus seropositivity is associated with the expansion of CD4+CD28- and CD8+CD28- T cells in rheumatoid arthritis

OBJECTIVE

Previous researchers have found expansion of CD4+CD28- T cells in patients with rheumatoid arthritis (RA) compared to age matched controls, and have identified expanded clones of autoreactive cells within this population. We examine the association of prior cytomegalovirus (CMV) infection (positive serum anti-CMV IgG) with the percentage of CD4+CD28- T cells and CD8+CD28- T cells in patients with RA.

METHODS

A total of 45 patients (36 women, 9 men), mean age of 59 years, with definite RA were studied.

RESULTS

In this group 28 patients were seropositive for CMV and 17 seronegative. Seropositive and seronegative subjects did not differ significantly in age, sex, medication use, or severity of disease. Joint count, Health Assessment Questionnaire, pain score, patient global assessment, physician global assessment, and presence of extraarticular disease served to assess disease severity. Expression of CD4/CD28/CD57 and CD8/CD28/CD57 on lymphocytes was determined by 3 color flow cytometry. (CD28 and CD57 are reciprocally related.) CD4+CD28-CD57+ T cells were expanded only in CMV seropositive patients.

CONCLUSION

The "carrier" phenotype that has been hypothesized based on a 2 population model for the distribution of CD4+CD28- T cells in RA can be explained by prior infection with CMV.

Detection of intracellular antigen-specific cytokines in human T cell populations

Determination of antigen-specific cytokine responses of T lymphocytes after vaccination is made difficult by the low frequency of responder cells. In order to detect these responses, the profile of intracellular cytokines was analyzed using flow cytometry after antigenic expansion. Peripheral blood mononuclear cells were stimulated with antigens for 5 days, further expanded with interleukin (IL)-2, and then restimulated on day 10. Cytokine production was detected by intracellular staining with monoclonal antibodies after saponin-based permeabilization. Influenza expansion resulted in specific interferon-gamma (IFN-gamma) production of 6%-20%, with less IL-4 production (0%-2%). Tetanus toxoid resulted in even greater production. IL-4 and IFN-gamma were produced mainly by memory cells of the CD45RO+ phenotype. IFN-gamma production was contributed by both CD4 and CD8 populations. These methods were then applied to a clinical trial of a candidate human immunodeficiency virus type 1 vaccine. Antigen-specific increases in IFN-gamma were measured, which corresponded to antibody production, lymphoproliferation, and skin testing.

Cytomegalovirus-specific IFNgamma and IL-4 are produced by antigen expanded human blood lymphocytes from seropositive volunteers

The cytokine responses to cytomegalovirus (CMV) antigen in seropositive and seronegative individuals were measured using a combination of antigenic expansion and intracellular staining. Intracellular IFNgamma and IL-4 were produced in a dose-dependent manner by T cells in response to CMV only in the seropositive population. The potential for individual cells to produce both Th1 and Th2 cytokines simultaneously was clear, as IL-4 was most often produced in those cells with the highest IFNgamma production. The cytokine-specific nature of this response was demonstrated by fluorescence microscopy, which showed granular cytoplasmic staining, and at the mRNA level by ribonuclease protection assays. These methods expand our ability to evaluate the immune response to CMV, and can now be correlated to a number of clinical conditions.