Self heat shock and gamma delta T-cell reactivity

Evidence for the divergence of innate and adaptive T-cell precursors before commitment to the αβ and γδ lineages

In addition to adaptive T cells, the thymus supports the development of unconventional T cells such as natural killer T (NKT) and CD8αα intraepithelial lymphocytes (IELs), which have innate functional properties, particular antigenic specificities, and tissue localization. Both conventional and innate T cells are believed to develop from common precursors undergoing instructive, TCR-mediated lineage fate decisions, but innate T cells are proposed to undergo positive instead of negative selection in response to agonistic TCR signals. In the present study, we show that, in contrast to conventional αβT cells, innate αβT cells are not selected against functional TCRγ rearrangements and express TCRγ mRNA. Likewise, in contrast to the majority of γδT cells, thymic innate γδT cells are not efficiently selected against functional TCRβ chains. In precursors of conventional T cells, autonomous TCR signals emanating from the pre-TCR or γδTCR in the absence of ligand mediate selection against the TCR of the opposite isotype and αβ/γδ lineage commitment. Our data suggest that developing innate T cells ignore such signals and rely solely on agonistic TCR interactions. Consistently, most innate T cells reacted strongly against autologous thymocytes. These results suggest that innate and adaptive T-cell lineages do not develop from the same pool of precursors and potentially diverge before αβ/γδ lineage commitment.

The innate immune response to uropathogenic Escherichia coli involves IL-17A in a murine model of urinary tract infection

Uropathogenic Escherichia coli is the causative agent for >80% of uncomplicated urinary tract infections (UTIs). Uropathogenic E. coli strains express a number of virulence and fitness factors that allow successful colonization of the mammalian bladder. To combat this, the host has distinct mechanisms to prevent adherence to the bladder wall and to detect and kill uropathogenic E. coli in the event of colonization. In this study, we investigated the role of IL-17A, an innate-adaptive immunomodulatory cytokine, during UTI using a murine model. Splenocytes isolated from mice infected by the transurethral route robustly expressed IL-17A in response to in vitro stimulation with uropathogenic E. coli Ags. Transcript expression of IL-17A in the bladders of infected mice correlated with a role in the innate immune response to UTI, and gammadelta cells seem to be a key source of IL-17A production. Although IL-17A seems to be dispensable for the generation of a protective response to uropathogenic E. coli, its importance in innate immunity is demonstrated by a defect in acute clearance of uropathogenic E. coli in IL-17A(-/-) mice. This clearance defect is likely a result of deficient cytokine and chemokine transcripts and impaired macrophage and neutrophil influx during infection. These results show that IL-17A is a key mediator for the innate immune response to UTIs.

Cryptosporidium parvum regulation of human epithelial cell gene expression

Cryptosporidium parvum is an obligate intracellular protozoan capable of causing life-threatening diarrhoeal disease in immunocompromised individuals. Efforts to develop novel therapeutic strategies have been hampered by the lack of understanding of the pathogenesis of infection. To better understand the host response to C. parvum infection, gene expression profiles of infected human ileocecal adenocarcinoma cells were analysed by using Affymetrix oligonucleotide microarrays containing probe sets for 12,600 human genes. Statistical analysis of expression data from three independent experiments identified 223 genes whose expression was reproducibly regulated by C. parvum infection at 24 h post-inoculation (125 up-regulated and 98 down-regulated), 13 of which were validated by quantitative reverse transcriptase polymerase chain reaction analysis. This analysis revealed the consistent up-regulation of host heat-shock genes and genes for pro-inflammatory chemokines IL-8, RANTES, and SCYB5. Multiple genes for host actin and tubulin genes were up-regulated whereas genes for actin binding proteins were down-regulated, confirming previous observations of host cytoskeleton rearrangement in response to C. parvum infection. In addition, host genes associated with cell proliferation and apoptosis were differentially regulated, reflecting the complexity of host-parasite interaction. Together, this study demonstrated that C. parvum infection results in significant changes in host biochemical pathways and provides new insights into specific biological processes of infectious disease caused by an intracellular protozoan parasite.

Infiltration of canonical Vgamma4/Vdelta1 gammadelta T cells in an adriamycin-induced progressive renal failure model

We have previously reported an infiltration of renal interstitial gammadelta T cells in Adriamycin-induced progressive glomerulosclerosis in the rat kidney. The TCR repertoire and sequences used by these gammadelta T cells have now been studied. Two injections of Adriamycin 14 days apart caused segmental glomerulosclerosis, massive interstitial infiltration of mononuclear cells, and end-stage renal failure. Flow cytometry of lymphocyte subpopulations with Abs to CD3, the gammadelta TCR, and the alphabeta TCR showed that gammadelta T cells as a proportion of CD3(+) cells were increased in Adriamycin-treated kidneys (8.5 +/- 5.4%), but not in lymph nodes (1.3 +/- 0.4%). A semiquantitative score of glomerular damage (r = 0.65; p < 0.01) and creatinine (r = 0.62; p < 0.01) correlated significantly with the presence of gammadelta T cells. TCR Vgamma repertoire analysis by RT-PCR and Southern blotting showed that Vgamma2 was the dominant subfamily in lymph nodes, whereas Vgamma4 became the predominant subfamily in advanced stages of the rat Adriamycin-treated kidney. Sequencing of the Vgamma4-Jgamma junctional region showed an invariant sequence. The amino acid sequence of the junctional region of the Vgamma4 TCR was the same as the reported mouse canonical Vgamma4 TCR sequence. Analysis of the kidney Vdelta repertoire showed dominant expression of Vdelta1, and sequencing again revealed the selective expression of a canonical Vdelta1 gene. Semiquantitative RT-PCR for cytokine gene expression showed that gammadelta T cells from the kidneys expressed TGF-beta, but not IL-4, IL-10, or IFN-gamma. These results suggest that the predominant gammadelta T cells in the Adriamycin kidney use an invariant Vgamma4/Vdelta1 receptor.

Innate immunity to viruses: control of vaccinia virus infection by gamma delta T cells

The existence of gammadelta T cells has been known for over 15 years, but their significance in innate immunity to virus infections has not been determined. We show here that gammadelta T cells are well suited to provide a rapid response to virus infection and demonstrate their role in innate resistance to vaccinia virus (VV) infection in both normal C57BL/6 and beta TCR knockout (KO) mice. VV-infected mice deficient in gammadelta T cells had significantly higher VV titers early postinfection (PI) and increased mortality when compared with control mice. There was a rapid and profound VV-induced increase in IFN-gamma-producing gammadelta T cells in the peritoneal cavity and spleen of VV-infected mice beginning as early as day 2 PI. This rapid response occurred in the absence of priming, as there was constitutively a significant frequency of VV-specific gammadelta T cells in the spleen in uninfected beta TCR KO mice, as demonstrated by limiting dilution assay. Also, like NK cells, another mediator of innate immunity to viruses, gammadelta T cells in uninfected beta TCR KO mice expressed constitutive cytolytic activity. This cytotoxicity was enhanced and included a broader range of targets after VV infection. VV-infected beta TCR KO mice cleared most of the virus by day 8 PI, the peak of the gammadelta T cell response, but thereafter the gammadelta T cell number declined and the virus recrudesced. Thus, gammadelta T cells can be mediators of innate immunity to viruses, having a significant impact on virus replication early in infection in the presence or absence of the adaptive immune response.

Distinct tumour specificity and IL-7 requirements of CD56(-)and CD56(+) subsets of human gamma delta T cells

gamma delta T cells are believed to recognize tissue injury caused by infections, tumours, as well as chemical and physical agents. The present study was carried out to study the feasibility of the ex vivo expansion of gamma delta T cells from healthy individuals, and to determine their functional capacity against tumours. We selectively expanded the peripheral gamma delta T cells of five donors against a myeloma cell line, XG-7. Under optimal conditions, the resulting bulk cultures comprised about 82% of the gamma delta T cells, more than 90% of which showed the T-cell receptor (TCR)-V gamma 9 delta 2 rearrangement. These gamma delta T-cell cultures exhibited TCR-gamma delta dependent cytotoxicity against different tumour cell lines including Molt-4, BJAB, Epstein-Barr virus (EBV) transformed lymphoid cell lines (LCL), and the nasopharyngeal carcinoma (NPC) cell lines, CNE2 and 915, in addition to the stimulator XG-7. By competitive cytotoxicity assays, the gamma delta T cells demonstrated recognition of at least three distinct target specificities expressed by Molt-4, CNE2 and LCL, respectively, which were related to that expressed by the stimulator XG-7 cells. The recognition of the specificity expressed by XG-7 and Molt-4 was further shown to require the participation of heat shock protein (HSP). The specificity expressed by CNE2 and 915 was preferentially recognized by the CD56 subset of gamma delta T cells, which could be sustained in the presence of interleukin (IL)-7. These results suggested that gamma delta T-cell immunity against tumour cell lines may be acquired in response to other types of tissue injury and, hence, implicates a role for their use in the prevention and treatment of tumours.

Co-stimulatory signals increase the reactivity of gammadelta T cells towards mycobacterial antigens

Although it has been shown that gammadelta T lymphocytes are able to react with different cell-associated or soluble antigens, the immune repertoire of these cells appears to be skewed to the recognition of mycobacterial antigens. We have studied the number and reactivity of gammadelta T cells towards several mycobacterial antigens in patients with tuberculosis and leprosy, as well as their healthy contacts and control individuals. We found an increased number of Vdelta2+ cells in healthy contacts (PPD+ and lepromin+) and tuberculoid leprosy patients. The gammadelta T cells from lepromatous leprosy showed a decreased response to all antigens tested, but some of these patients exhibited a significant response to the 30-kD glycoprotein of Mycobacterium tuberculosis. Interestingly, the reactivity of gammadelta T cells against mycobacterial antigens was significantly increased by costimulatory signals generated through CD7, LFA-1, CD50 and CD69 in all groups. However, signalling through CD69 did not enhance the responsiveness of gammadelta lymphocytes from lepromatous patients. On the other hand, the in vitro blockade of IL-10 with a specific antibody enhanced the cell proliferation of gammadelta lymphocytes from lepromatous leprosy patients, whereas exogenous IL-10 had an opposite effect in most individuals studied. These results suggest the potential role of different cell membrane receptors in the regulation of gammadelta T cell proliferation induced by mycobacteria, as well as the possible involvement of IL-10 in this phenomenon.

Vgamma1+ gammadelta T cells play protective roles at an early phase of murine cytomegalovirus infection through production of interferon-gamma

Cytomegalovirus (CMV) causes severe opportunistic infection in immunocompromised hosts. The importance of conventional alphabeta T cells in protection against CMV infection has been well documented. However, the role of the second T-cell population (which express the gammadelta T-cell receptor) in CMV infection is not known. In the present study, we analysed the function and protective role of gammadelta T cells in a murine cytomegalovirus (MCMV) infection model. After intraperitoneal infection with MCMV, the number of gammadelta T cells increased in the liver and peritoneal cavity from day 3, and reached a peak on day 5. The gammadelta T cells showed an activated T-cell phenotype and predominantly expressed Vgamma1, which is known to be expressed by heat-shock protein 65 (hsp 65)-specific gammadelta T cells. Analysis of cytokine expression demonstrated that the MCMV-induced gammadelta T cells expressed interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) but not interleukin-4 (IL-4), implying their participation in the cell-mediated immune response against MCMV. Depletion of gammadelta T cells by anti-T-cell receptor (TCR) gammadelta monoclonal antibody (mAb) treatment resulted in significant increase of virus titre and decrease of IFN-gamma in the liver on day 3 after MCMV infection, which further supports the importance of gammadelta T cells in early protection against infection. Finally, the MCMV-induced gammadelta T cells produced IFN-gamma in vitro in response to hsp 65. Our results suggest that gammadelta T cells participate in early protection against MCMV infection through recognition of hsp 65 and production of IFN-gamma.

Heat Shock Protein 70 Induced During Tumor Cell Killing Induces Th1 Cytokines and Targets Immature Dendritic Cell Precursors to Enhance Antigen Uptake

Previously, we reported that killing tumor cells in vivo with the HSV thymidine kinase/ganciclovir system generates potent antitumor immunity, determined in part by the mechanism by which the cells die and by the levels of inducible heat shock protein (hsp) expression induced during the process of cell death. Here, we show that induction of hsp70 expression induces an infiltrate of T cells, macrophages, and predominantly dendritic cells (DCs) into the tumors as well as an intratumoral profile of Th1 cytokine expression (IFN-γ, TNF-α, and IL-12) and enhances immunogenicity via a T cell-mediated mechanism. In addition, the protection conferred by hsp70 is both tumor and cell specific. We also demonstrate that hsp70 targets immature APC to make them significantly more able to capture Ags. This is likely to optimize cross-priming of the infiltrating APC with tumor Ags, which are simultaneously being released by the dying cells. In addition, using an Myc epitope-tagged hsp70 expression vector, we present evidence that hsp70 released from dying tumor cells is taken up directly into DCs and may, therefore, be involved in direct chaperoning of Ags into DCs. Taken together, our data suggest that hsp70 induction serves to signal the immune system of the presence of an immunologically relevant (dangerous) situation against which an immune reaction should be raised.

Inflammation Alone Evokes the Response of a TCR-Invariant Mouse γδ T Cell Subset

Whether γδ T lymphocytes respond to microbial Ags or to inducible host Ags remains a matter of controversy. Using several different disease models and mouse strains, we and others have seen that Vγ6/Vδ1 γδ T cells preferentially increase among the γδ T cells infiltrating inflamed tissues. However, it was not clear whether bacteria are necessary to bring about this response. Therefore, we have reexamined this question using a disease model in which inflammation is induced by a purely autoimmune process involving no bacteria, bacterial products, or other foreign material: testicular cell-induced autoimmune orchitis. Using this model we found that γδ T cells were still plentiful among the infiltrating T lymphocytes, being 9- to 10-fold more prevalent than in spleen, and that Vγ6/Vδ1+ cells again represented the predominant γδ T cell type. This finding shows that the response of the Vγ6/Vδ1+ subset does not, in fact, depend upon the presence of bacteria or bacterial products. The stimulus triggering the response of the Vγ6/Vδ1 γδ T cells appears to be neither foreign nor organ-specific in origin, but instead consists of a self-derived host Ag or signal induced during the inflammatory process.

MHC Class II-Dependent NK1.1+ γδ T Cells Are Induced in Mice by Salmonella Infection

We observed the emergence of a novel population of γδ T cells expressing NK1.1 Ag in the peritoneal cavity of mice infected with Salmonella choleraesuis. The NK1.1+γδ T cells accounted for approximately 20% of all γδ T cells emerging in the peritoneal cavity of C57BL/6 mice and expressed preferentially rearranged Vγ4-Jγ1 and Vδ6.3-Dδ1-Dδ2-Jδ1 genes with N diversity. The γδ T cells proliferated vigorously in response to PHA-treated spleen cells and produced IFN-γ in the culture supernatant. However, spleen cells from Aβb-deficient mice were unable to stimulate the γδ T cells. Furthermore, the NK1.1+γδ T cells were stimulated not only by Chinese hamster ovary (CHO) cells expressing wild-type IAb but also by those expressing IAb/Eα52-68 or IAb/pigeon cytochrome c-derived analogue peptide complex. These proliferation activities were inhibited by mAb specific for IAb chain. Consistent with these findings, the emergence of NK1.1+γδ T cells was reduced in the peritoneal cavity of Aβb-deficient mice after Salmonella infection, whereas NK1.1+γδ T cells were rather abundant in the peritoneal cavity of Salmonella-infected β2m-deficient mice. Moreover, the NK1.1+γδ T cells were easily identified in the thymus of β2m-deficient but not Aβb-deficient mice. Our results indicated that MHC class II expression is essential for development and activation of NK1.1+γδ T cells in the thymus and the periphery.

Can immunotherapy by gene transfer tip the balance against colorectal cancer?

Gene therapy, in particular the transfer of genes encoding immunostimulatory molecules (cytokines and costimulatory molecules) as well as selectively cytotoxic enzymes and DNA vaccination, has the potential of enhancing cell mediated immune responses against tumours including those of colorectal origin. Genes can be transferred using viral vectors either to cultured tumour cells in vitro that can be returned to the patient as a "cancer vaccine", or directly to tumour cells in vivo. Vaccination with DNA constructs expressing specific tumour antigens characteristic of colorectal neoplasia can trigger immune recognition and destruction of tumour cells. The aim is to tip the balance from protumour to antitumour mechanisms by generating a local immune response and systemic antitumour immune memory to destroy metastases. Studies in murine models, combined with human studies, show that such approaches could become an adjunct to current treatments for human colorectal cancer in the near future.

Gamma delta T-cells in human cutaneous immunology

Gamma delta T-Cells represent a minor subpopulation of T-lymphocytes in man and their role in normal and diseased human skin is unknown. This article is a comprehensive review of T-lymphocytes bearing the gamma delta T-cell receptor in normal and pathological human skin. Firstly, we have documented the occurrence of gamma delta T-cells in normal skin and in a range of reactive and malignant skin conditions. We have then discussed the experimental findings regarding the repertoire used by gamma delta T-cells in normal human skin and in cutaneous disorders with an increased percentage of gamma delta T-cells.

Phenotypic characterization of lymphocyte subpopulations in horses affected with chronic obstructive pulmonary disease and in normal controls

The alterations in lymphocyte subsets in chronic obstructive pulmonary disease (COPD) in the horse were investigated by using monoclonal antibodies to identify CD3+, CD4+, CD8+, and surface immunoglobulin positive (sIg+) lymphocytes in peripheral blood, bronchoalveolar lavage fluid (BALF), and pulmonary biopsy frozen tissue sections. COPD-affected horses (n = 5) and normal controls (n = 5) were sampled prestabling and 14 days poststabling, at which time the COPD-affected horses wee exhibiting clinical signs of COPD. The peripheral blood absolute CD4+ lymphocyte count was significantly elevated in the COPD-affected horses pre- and poststabling. The CD4:CD8 ratio in peripheral blood of COPD-affect horses was unaffected by stabling, but the same ratio in the control horses was significantly decreased. These findings support a hypothesis of deficient regulation of a systemic immune response to indoor air in the COPD-affected horses. A large population of leukocytes in pulmonary biopsy immunohistochemical sections from both groups of horses appeared to be CD3+ CD4- CD8-, an uncommon phenotype in both the peripheral blood and BALF.

gamma delta cells involved in contact sensitivity preferentially rearrange the Vgamma3 region and require interleukin-7

Ptak and Askenase showed that both alphabeta and gammadelta cells are required for transfer of contact sensitivity (CS). This study confirms that day 4 immune cells depleted of gammadelta cells fail to transfer CS to trinitrochlorobenzene (TNP-Cl) systemically and demonstrates that administration of anti-gammadelta monoclonal antibodies (mAb) in vivo abolishes the CS reaction. Moreover, gammadelta cells accumulate at the antigen challenge site: these cells have the unusual phenotype CD8alpha+, CD8beta-, IL-4 R+ which we suggest is due to their state of activation. Following immunization with contact sensitizer on the skin, the absolute number of gammadelta cells increases in the regional lymph nodes with a peak at 4 days. Of the gammadelta cells, 80 %, both in the lymph nodes of TNP-Cl-immune mice and accumulating at the antigen challenge site are Vgamma3+. The gammadelta cells expressing Vgamma3, which is characteristic of dendritic epithelial T cells (DETC), obtained 4 days after sensitization, proliferate in response to interleukin (IL)-7, but only poorly to IL-2 and IL-4. They also respond to concanavalin A and immobilized anti-gammadelta mAb, but not to haptens or heat-shocked syngeneic spleen cells. Furthermore, injection of mice with mAb to IL-7 inhibits accumulation of Vgamma3+ cells both in the lymph nodes after skin sensitization and at the antigen-challenge site. Altogether, these results strongly support the view that DETC are related to, or the original source of, the gammadelta cells found in the lymph node after skin sensitization and at the site of challenge, and that IL-7 is implicated in these phenomena.

Oligoclonal expansion of gamma delta T cells in cerebrospinal fluid of multiple sclerosis patients

We have used a PCR based method to analyse TCR gamma chain repertoire and clonality of gamma delta T cells in the CSF and blood of II MS patients. Samples collected from nine patients with other neurological diseases were used as a control. Five controls had central nervous system inflammation and four had non-inflammatory processes. We have observed a decreased percentage of gamma delta T cells expressing TCR gamma with V gamma 9 and J gamma P fragments in the CSF samples in comparison with the blood. We did not final clonal expansion of the gamma delta T cells in any control case. Clonal expansion of gamma delta T cells occurred in five of II MS cases in the CSF but not in the blood. Two of these clones expressed TCR gamma rearranged with V gamma 9 and J gamma 1 fragments, two others used V gamma 10 and J gamma P1, and one used V gamma 9 and J gamma P fragments. We found no correlation between clonality and clinical state of patients, duration of the disease or number of cells in CSF. Our study provides additional evidence for the possible role of the gamma delta T cells in the MS pathogenesis.

Alpha/beta- and gamma/delta-T-cell-receptor-positive lymphocytes in healthy and inflamed human conjunctiva

BACKGROUND

The possible existence and distribution patterns of alpha/beta- and gamma/delta-TCR+ cells, which are important constituents of immune surveillance and act via the CD3+ cell complex have not yet been elucidated in the healthy and inflamed conjunctiva.

MATERIALS AND METHODS

Paraffin-embedded conjunctival specimens included 18 from 18 patients with ocular cicatricial pemphigoid (OCP), 20 from 20 healthy controls, 6 from 6 patients with lye burns, and 6 from 2 patients with Stevens-Johnson syndrome; all were worked up by histology and immunohistochemistry.

RESULTS

alpha/beta-TCR+ cells were visualized in the conjunctival epithelium and stroma of healthy persons, OCP, lye burns and Stevens-Johnson syndrome. alpha/ beta-TCR+ cells and a small number of gamma/delta-TCR+ cells were observed in the corneal epithelium and stroma of patients who have failing corneal grafts. After ileal mucosa transplantation to the epibulbar conjunctiva, membrane staining changes to nuclear and cytoplasmic staining. Treatment with systemic cytotoxic drugs abolishes all alpha/beta-TCR+ and gamma/delta-TCR+ cells.

CONCLUSIONS

alpha/beta-TCR+ cells can be found in the non-infected epithelium and stroma of the healthy and inflamed (OCP, lye burns, and Stevens-Johnson syndrome) conjunctiva, as well as in the corneal epithelium and stroma of failing corneal grafts, whereas gamma/delta-TCR+ cells are absent. A small number of gamma/delta-TCR+ cells are present in the corneal stroma and adjacent conjunctival epithelium of patients with chronic corneal graft rejection or after transplantation of gut tissue. Further investigations may establish the role, if any, of these T-cell subsets in immune surveillance of the non-infected outer eye and in corneal graft rejection.

Positive selection is not required for thymic maturation of transgenic gamma delta T cells

Previously published reports describing thymic differentiation in two TCR gamma delta transgenic mouse models have suggested that gamma delta T cells require MHC-mediated positive selection to reach full maturity. Recent studies indicate that recognition of antigen by mature gamma delta T cells is not MHC restricted, raising the issue of why developing gamma delta T cells would even require MHC-driven positive selection. Therefore, we have reinvestigated the requirements for development and selection in G8 gamma delta T cell receptor (TCR) transgenic mice. Analyses of absolute cell numbers, phenotypic subsets, and functional competence of thymic and peripheral G8 gamma delta T cells indicate that these cells can fully mature in class I MHC-deficient mice. Moreover, mixed bone marrow chimeras demonstrate that gamma delta T cells of mutant B2-microglobulin (beta 2m zero) origin are partially deleted in the presence of H-2d-bearing thymocytes (previously believed to be the haplotype mediating positive selection). We conclude that there is no requirement for class I-like molecules for the maturation/development of these transgenic gamma delta T cells and that the differences in thymocyte phenotype and number observed are, instead, attributable to effects of clonal deletion.

gamma/delta and other unconventional T lymphocytes: what do they see and what do they do?

T lymphocytes recognize specific ligands by clonally distributed T-cell receptors (TCR). In humans and most animals, the vast majority of T cells express a TCR composed of an alpha chain and a beta chain, whereas a minor T-cell population is characterized by the TCR gamma/delta. Almost all of our knowledge about T cells stems from alpha/beta T cells and only now are we beginning to understand gamma/delta T cells. In contrast to conventional alpha/beta T cells, which are specific for antigenic peptides presented by gene products of the major histocompatibility complex, gamma/delta T cells directly recognize proteins and even nonproteinacious phospholigands. These findings reveal that gamma/delta T cells and alpha/beta T cells recognize antigen in a fundamentally different way and hence mitigate the dogma of exclusive peptide-major histocompatibility complex recognition by T cells. A role for gamma/delta T cells in antimicrobial immunity has been firmly established. Although some gamma/delta T cells perform effector functions, regulation of the professional and the nonprofessional immune system seems to be of at least equal importance. The prominent residence of gamma/delta T cells in epithelial tissues and the rapid mobilization of gamma/delta T cells in response to infection are consistent with such regulatory activities under physiological and pathologic conditions. Thus, although gamma/delta T cells are a minor fraction of all T cells, they are not just uninfluential kin of alpha/beta T cells but have their unique raison d'être.

Noncytotoxic alkyl-lysophospholipid treatment increases sensitivity of leukemic K562 cells to lysis by natural killer (NK) cells

Alkyl-lysophospholipids (ALP) are a group of anti-cancer compounds tha t have previously been shown to have the unique feature of being selectively toxic to neoplastic tissues. Because alkyl-lysophospholipids target the cell membrane as their site of action, our aim was to analyse the immunological effects of a nonlethal ALP treatment on leukemic K562 cells. In this in vitro study we used ET-18-OCH3, one of the most potent ALP derivatives, at different concentrations ranging from 25 up to 100 microgram/ml. By measurement of cell viability and of apoptosis, we determined a concentration of 25 microgram/ml ET-18-OCH3 and an incubation period of 2 hr as nonlethal for K562 cells; higher concentrations markedly reduced cell viability and led to induction of apoptosis. Similar to the effects induced by nonlethal heat shock, a nontoxic ET-18-OCH3 treatment led to a significant increase in the sensitivity of K562 cells to lysis by interleukin-2 (IL-2) stimulated natural killer (NK) cells. With respect to these results, we investigated the influence of nonlethal ALP treatment on the cell surface expression patterns and compared it to the results obtained with nonlethal heat shock. ALP treatment does not induce major histocompatibility complex (MHC) expression; however, a significant increase in the cell surface expression of HSP72 was shown by immunoblot analysis of membrane lysates of either untreated or ET-18-OCH3 treated K562 cells. The increased sensitivity of ET-18-OCH3 treated K562 cells to lysis by NK cells could be correlated with the elevated cell surface expression of HSP72.

Depletion of gamma/delta T cells does not prevent or ameliorate, but rather aggravates, rat adjuvant arthritis

OBJECTIVE

To investigate the role of gamma/delta T cells in Mycobacterium tuberculosis-induced rat adjuvant arthritis.

METHODS

Rats with adjuvant arthritis were injected with anti-T cell receptor gamma/delta (anti-TCRgamma/delta) monoclonal antibody V65 according to a preventive protocol, a pre-arthritis peak protocol, and a late therapeutic protocol. Arthritis severity and joint destruction were monitored, and depletion of target cells was analyzed by flow cytometry.

RESULTS

Although all protocols led to successful depletion of TCRgamma/delta(bright) cells in peripheral blood and lymph nodes, none of the regimens influenced clinical parameters of adjuvant arthritis. If rats were treated before the clinical peak of adjuvant arthritis, however, joint destruction was significantly more severe than in vehicle-treated rats.

CONCLUSION

Rat adjuvant arthritis is not promoted or perpetuated by gamma/delta T cells. Aggravation of joint destruction with pre-arthritis peak anti-gamma/delta treatment suggests a stage-dependent protective role of gamma/delta T cells in adjuvant arthritis.

Interleukin (IL)-15 promotes the growth of murine epidermal gamma delta T cells by a mechanism involving the beta- and gamma c-chains of the IL-2 receptor

Dendritic epidermal T cells (DETC) are skin-specific members of the epithelial gamma delta T-cell family in mice. We have reported previously that the growth of DETC is promoted by interleukin (IL)-2 in an autocrine fashion, or by IL-7, which is secreted by neighboring keratinocytes. Here we report that DETC growth is promoted by IL-15, a newly discovered T-cell growth factor that is produced in lymphoid as well as nonlymphoid tissues. Recombinant IL-15 promoted the growth of the 7-17 DETC line in a time- and dose-dependent fashion. Using monoclonal antibodies against alpha-, beta-, or gamma c-chains of the IL-2 receptor complex, we observed that the combination of anti-beta chain and anti-gamma c chain antibodies blocked IL-15 responsiveness completely, whereas anti-alpha chain had no effect. These results indicate that this gamma delta T-cell line uses the beta/gamma c heterodimer for proliferative responses to IL-15. Antibodies against IL-2 or IL-7 did not block IL-15-driven proliferation of 7-17 DETC, indicating that IL-15 promotes their growth in an IL-2- and IL-7-independent manner. Both the surface expression of beta/gamma c heterodimers and the IL-15 responsiveness of 7-17 DETC were highest 1 to 8 days after concanavalin A stimulation, and both declined substantially 21 days after stimulation, illustrating regulation by the state of cell activation. Working with epidermal cells that were freshly procured from CBA mice, we noted that IL-15 promoted conavalin-A-triggered growth of Thy-1+ cells (i.e., DETC), but not of the Thy-1- cells. The gamma c-chain was not expressed by freshly procured DETC, becoming detectable within 48 h after concanavalin A stimulation. We propose that IL-15 facilitates the growth of epithelial gamma delta T cells by a beta/gamma c receptor-dependent mechanism.

Gamma delta T lymphocytes in human periodontal disease tissue

Gamma delta T cells have been implicated as playing a role in inflammatory and autoimmune conditions. In this study, a biotin-streptavidin peroxidase technique was used to determine the presence of T cells expressing alpha beta and gamma delta T cell receptors (TCR) in the inflammatory infiltrates of gingival tissue sections from gingivitis and adult periodontitis patients. The lesions were graded 1+ to 3+ according to the size of the infiltrate. alpha beta+ T cells predominated in all infiltrates with no differences in the mean percent (20 to 30%) according to size of lesion or to clinical status. A mean percent gamma delta T cells of 0.42 +/- 0.11 and 0.91 +/- 0.42 was demonstrated in 1+ infiltrates of gingivitis and adult periodontitis sections respectively. Although the mean percent gamma delta T cells increased in both gingivitis (2.09 +/- 0.54) and adult periodontitis sections (2.25 +/- 0.35) with increasing size of infiltrate, this was not statistically significant. However, when the mean proportion of gamma delta T cells of the total TCR bearing cells was determined, there was a significant 3 to 4 fold increase in adult periodontitis sections from 3.09 +/- 1.35 in 1+ lesions to 11.90 +/- 2.94 and 8.81 +/- 1.45 in 2+ and 3+ lesions respectively. A similar increase of the same magnitude occurred in gingivitis sections from 2.82 +/- 0.74 in 1+ lesions to 11.12 +/- 4.13 in 2+ lesions, but this was not significant (P = 0.055). There was no correlation between the increase in the proportion of gamma delta T cells and the T:B cell ratio or the CD4:CD8 ratio in individual lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Gamma delta T cell receptor analysis supports a role for HSP 70 selection of lymphocytes in multiple sclerosis lesions

BACKGROUND

Interactions between gamma delta T cells and heat shock proteins (HSP) have been proposed as contributing factors in a number of diseases of possible autoimmune etiology but definitive evidence to support this hypothesis has been lacking. In multiple sclerosis (MS), a chronic inflammatory neurologic disease, HSP and gamma delta T cells are known to colocalize in brain lesions. Analysis of T cell receptor (TCR) gene usage in these lesions has detected evidence of clonality within both the V delta 2-J delta 1 and V delta 2-J delta 3 populations of gamma delta T cells. In our own studies, using direct sequence analysis, a dominant V delta 2-J delta 3 TCR sequence was found in 9 MS brain samples, suggesting a response to a common antigen. In this report, we have examined gamma delta T cell receptor gene usage in MS peripheral blood T cell lines selected for reactivity to HSP 70.

MATERIALS AND METHODS

TCR rearrangement patterns for V delta 2-J delta 1 and V delta 2-J delta 3 were studied using the polymerase chain reaction (PCR) and a direct sequencing technique in populations of peripheral blood mononuclear cells (PBMC) cultured with Mycobacterium tuberculosis (M. tuberculosis) purified protein derivative (PPD) and then selected for reactivity to a 70-kD heat shock protein (HSP70). Cells were obtained from health donors, patients with MS, and patients with tuberculosis (TB). PCR products were subjected to direct sequence analysis to look for evidence for clonality within these T cell lines and to define the sequence of the V-D-J (CDR3) region of the TCR.

RESULTS

In freshly isolated PBMC, both V delta 2-J delta 1 and V delta 2-J delta 3 gene rearrangement patterns were detected, whereas in HSP70+ T cell lines the predominant delta chain rearrangement pattern was V delta 2-J delta 3. Direct sequence analyses indicated that in cells reactive with HSP70 the V delta 2-J delta 3 sequences were usually oligoclonal and used D delta 3 exclusively. In four of four MS and two of three TB patients, the oligoclonal sequences in the HSP70+ T cell lines were identical to one another and to a dominant sequence previously detected in MS brain lesions. In two of three HSP70+ T cell lines from healthy controls, the oligoclonal sequences differed from those found in both groups of patients but were identical to one another except for a small region of heterogeneity in the second N region. In contrast, in freshly isolated PBMC or in PPD+HSP70- T cell lines, the V delta 2-J delta 3 gene rearrangement patterns were usually polyclonal and dominant sequences were rarely identified.

CONCLUSIONS

These results support the conclusion that a subpopulation of gamma delta T cells in MS lesions are responding to HSP 70 and that non-CNS-specific antigens contribute to the pathogenesis of MS.

Immunohistochemical study of gamma delta T cell receptor-positive cells in the capsular region of hepatocellular carcinoma: possible role in defense against expansion of carcinoma in the liver

The localization and distribution of gamma delta T cell receptor (TCR)-positive cells (gamma delta T cells) in hepatocellular carcinoma capsules was investigated immunohistochemically at both light and electron microscopic levels. Most of the mononuclear cells infiltrating the tumor capsules were CD3-positive. Together with gamma delta T cells, they were significantly increased in the tumor capsules compared to amounts in the fibrous septa in non-cancerous cirrhotic areas of the same liver, and compared to amounts in the liver of patients with cirrhosis. Phenotypic characterization by the two-color double-staining technique showed that CD8/gamma delta cells were significantly increased in the tumor capsule, and that more than one-third of gamma delta TCR-positive cells also expressed the CD56 antigen. Morphological observation revealed that large gamma delta T cells were increased in number in the tumor capsule and that the cytoplasm of these cells contained multivesicular bodies and dense granules. These morphological features were similar to those of large granular lymphocytes, and most of the gamma delta T cells were also positive for BB3. This suggests that extrathymic maturation of gamma delta T cells occurs in the tumor capsule, and that these gamma delta T cells may have a cytolytic effect on tumor cells, as shown in large granular lymphocytes; further, the results suggest that these cells may play a role in the defense against tumor expansion.

Multiple sclerosis: limited diversity of the V delta 2-J delta 3 T-cell receptor in chronic active lesions

T lymphocytes bearing the gamma delta T-cell receptor have been found in the central nervous system of patients with multiple sclerosis in association with demyelinated lesions. Although the biological function of these cells remains to be established, it has been proposed that they are involved in the response to highly conserved antigens, such as heat shock proteins (hsp), expressed during tissue damage and thus may contribute to the development of an autoimmune response. Using polymerase chain reaction, we probed for the presence of T-cell receptor gamma delta cells in fresh-frozen early autopsy brain tissue from patients with multiple sclerosis and patients with non-multiple sclerosis conditions. The results demonstrated the presence of two major V-J combinations of the T-cell receptor delta chain--V delta 2-J delta 3, V delta 2-J delta 1--and we used a direct sequencing technique to determine whether this gamma delta T-cell population was clonal or diverse. In chronic-active plaques from 9 patients with multiple sclerosis, we found a striking predominant gene rearrangement within the V delta 2-J delta 3 T-cell receptor population that was not present in central nervous system tissue from patients with other neurological diseases. In contrast, within the V delta 2-J delta 1 T-cell receptor population, a predominant rearrangement pattern was detected in only 1 of the multiple sclerosis patients. The sequence of the predominant V delta 2-J delta 3 gene rearrangement was confirmed by cloning and sequencing the gene products from 1 multiple sclerosis patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocyte proliferation in mice congenitally deficient in T-cell receptor alpha beta + cells

In mice and humans, T cells are characterized on the basis of T-cell receptor (TcR) expression and divided into the major TcR alpha beta + and minor TcR gamma delta + populations. TcR alpha beta + cells are considered to be the primary regulators of the immune response, whereas the function of TcR gamma delta + cells is unclear. Mice congenitally deficient in TcR alpha beta-expressing cells provide an ideal model for analyzing the independent in vivo function of TcR gamma delta + cells in the absence of TcR alpha beta + cells. Here we report that lymphoid organs in TcR alpha mutant mice undergo substantial enlargement after being challenged by environmental antigens. This organ expansion can be attributed in part to increases in the relative proportions and absolute numbers of TcR gamma delta + cells, but an expansion of the recently described TcR beta + alpha - population also has a role. The expansion of the TcR gamma delta + population is polyclonal, as evidenced by the usage of multiple gamma and delta variable chain segments. Furthermore, a substantial proportion of the cells appears to be activated and these activated cells express surface activation markers. The results clearly demonstrate that TcR gamma delta + cells proliferate independently in response to a broad spectrum of challenges. Moreover, since the expansion of the lymphoid tissues and the TcR gamma delta + cell population is excessive relative to that seen in wild-type animals, one role of TcR alpha beta + cells is directly or indirectly to limit the responses of the other lymphoid components.

Association of increased numbers of peripheral blood double-negative T-lymphocytes with elevated serum IgG levels in severely handicapped children

CD3+4-8- double negative cells in peripheral blood lymphocytes were examined in 21 severely handicapped children divided into two groups according to serum IgG level. All children were bedridden and were taking multiple anticonvulsants and there were no apparent clinical differences between these two groups. Serum levels of IgG correlated well with percentages of CD3+4-8- double negative lymphocytes in patients of both groups. In comparisons between the two groups, the high IgG group had higher counts of CD3+4-8- double negative lymphocytes in peripheral blood than the normal IgG group. Two distinct types of double negative cells were identified in the patients with high IgG: one had T-cell antigen receptors of gamma delta heterodimers, the other had receptors of alpha beta chains on their surface. As double negative T-cells are reported to have an important role in defence against bacterial infections, the increased numbers of CD3+4-8- T-cells of both phenotypes in the high IgG patients may reflect exposure to repetitive bacterial stimuli or persistent subclinical infection which in many cases, may be undetectable clinically. Moreover, the hyperimmune states shown by the high serum IgG of these patients may result from the appearance of these unique lymphocytes because they are reported to have a helper function for IgG synthesis in vitro. Taken together, the increased numbers of double negative cells in patients with high IgG may reflect activated defence mechanisms and the development of hyperimmune status.

V delta 1+ gamma/delta T lymphocytes infiltrating human lung cancer express the CD8 alpha/alpha homodimer

Murine gamma/delta T lymphocytes localize to different epithelial tissues and are phenotypically distinct from peripheral gamma/delta T cell-populations in that they show limited TCR diversity, express the CD8 alpha/alpha homodimer and lack the CD8 beta chain. In humans, a compartmentalization of gamma/delta cells sharing similar phenotypic features has been documented to date only in the case of intestinal epithelium. In the present study we show that about half of V delta 1+ (as well as V delta 1-V delta 2-) gamma/delta lymphocytes, which can be selectively expanded from human lung cancers, coexpress the CD8 alpha/alpha homodimer. The accumulation of intraepithelial CD8+ gamma/delta+ lymphocytes might then be a more general phenomenon, possibly as a result of common mechanisms operating at those sites.

Sendai virus pneumonia: evidence for the early recruitment of gamma delta T cells during the disease course

We previously reported that gamma delta T cells appeared and could play a protective role early in infections with intracellular bacteria such as Listeria monocytogenes, Mycobacterium bovis BCG, and Salmonella choleraesuis. To extend these findings to virus infection, we examined the developmental sequence of gamma delta T cells in bronchoalveolar lavage during the course of Sendai virus infection in C57BL/6 mice. To produce a natural but nonlethal infection course as far as possible, we used a sublethal dose of a wild-type virus which had not been subjected to serial passages in a chicken embryo, hence retaining full virulence for mice. Virus titers in lungs reached a peak on day 6 and then decreased to an undetectable level by day 10. This time course of virus reproduction was immediately and coincidentally followed by the developmental course of gamma delta T cells, in which the cell number peaked on day 7 and then decreased to a marginal level by day 10. On the other hand, the alpha beta T-cell number continued to increase until day 10 and remained at a high level thereafter. The early-appearing gamma delta T cells were CD4-, CD8-, IL-2R alpha- beta+, CD44+, Mel-14-, and LFA-1 alpha/beta+ in phenotype and used V gamma 1/2 and V gamma 4 and V delta 3, V delta 4, V delta 5, and V delta 6. The gamma delta T cells were responding to macrophages from infected mice when the cells were cultured in vitro. Furthermore, the expression of endogenous heat shock protein (hsp) was infection specific, and its level appeared to correlate with the gamma delta T-cell development. These results suggest that the early recruitment of gamma delta T cells, which proliferate in response to endogenous hsp+ cells, is also characteristic of this virus infection, although this view appears to be contradictory to earlier reports.

Distinct pattern of HSP72 and monomeric laminin receptor expression in human lung cancers infiltrated by gamma/delta T lymphocytes

We have previously demonstrated that gamma/delta T lymphocytes may participate in the host immune response against lung adenocarcinomas. Here we show that, in about one-fourth of human lung cancers, gamma/delta T cells represented a significant proportion of freshly isolated tumor-infiltrating lymphocytes. Moreover, these cells selectively expand in vitro upon culture in the presence of IL-2, thus suggesting a prior activation in vivo. Finally, when we evaluated the expression of heat shock proteins and of a panel of tumor-associated antigens in lung cancers infiltrated by gamma/delta vs. alpha/beta T cells, we found that the former displayed a distinct antigenic pattern, characterized by over-expression of HSP72 and of the 67-kDa high-affinity laminin receptor, which might account for gamma/delta T-cell recognition.

gamma delta T-cell receptor-positive cells of human skin. II. Appearance in delayed-type hypersensitivity reaction

In order to investigate the distribution and involvement of human gamma delta T-cell receptor-positive (TCR+) cells in delayed-type hypersensitivity reactions of the skin, we examined the occurrence and kinetics of gamma delta TCR+ cells during skin reactions of allergic contact dermatitis. In normal human skin sections, gamma delta TCR+ cells were scarce. In allergic contact dermatitis from DNCB, increased gamma delta TCR+ cells were observed both in the epidermis and in the dermis from 48 h after the challenge. Most of the gamma delta TCR+ cells were TCR delta 1+ delta TCS1- BB3+ Ti gamma A+ (V delta 1- V delta 2+ V gamma 9+). The percentage of gamma delta TCR+ cells in the peripheral blood remained unchanged and a few gamma delta TCR+ cells in the skin lesions proliferated in situ. It is suggested that the gamma delta TCR+ cells in skin lesions of allergic contact dermatitis may not be involved in initiation of delayed-type hypersensitivity but may have some other roles responding to factors induced in the reaction.

Brefeldin A blocks the cytotoxicity of T cell receptor alpha/beta and gamma/delta cytotoxic T lymphocyte clones reacting against human autologous cancer cells

We studied the effector mechanism of T cell receptor (TCR) alpha/beta- and gamma/delta-type cytotoxic T lymphocyte (CTL) clones that react with human autologous tumor cells. Treatment of tumor cells with a fungal antibacterial reagent, brefeldin A (BFA), resulted in the inhibition of cytotoxicity of an autologous tumor (HST-2)-specific CD8+ TCR alpha/beta-type CTL, TcHST-2. Other anti-metabolites such as chloroquine, cycloheximide and colchicine did not affect the cytotoxicity. The cell-surface antigen expression, including MHC class I molecules, was not influenced by BFA treatment. Furthermore, BFA did not influence the cytotoxicity of lymphokine-activated killer cells and natural killer cells. Since BFA blocks the transport of peptides from endoplasmic reticulum to the Golgi apparatus, the above data suggest that BFA could affect washing out of the peptide fragments from the MHC class I groove. Consequently, target tumor cells were protected from killing by CTL. Moreover, we obtained a CD4-, 8-, TCR gamma/delta-type (V delta 1+) CTL clone, TcHOT, that reacts against an autologous ovarial carcinoma, HOT. BFA could also inhibit this cytotoxicity, and it is likely that different presenting molecules other than MHC class I proteins participate in the cytotoxicity of this TCR gamma/delta-type CTL. These studies suggest that both TCR alpha/beta- and gamma/delta-type CTL may require antigenic peptides that are most likely derived from the BFA-sensitive, intracellular endogenous target proteins.

Molecular analysis of the gamma delta T-cell receptor repertoire in normal human skin and in Oriental cutaneous leishmaniasis

The extent of diversity of the gamma delta T-cell receptor (TCR) in normal human skin and Oriental Cutaneous Leishmaniasis (OCL) was examined by molecular analysis of the variable (V) delta gene segment, junctional (J) delta gene segment and junctional regions. To examine the expression of TCR delta genes, segments of gamma delta T lymphocytes, DNA isolated from normal human skin and from OCL were subjected to enzymatic gene amplification by the polymerase chain reaction (PCR) method using TCR V delta- and J delta-specific oligonucleotides as primers. PCR amplification using these primers indicated that the V delta 2 gene segment was predominantly used by gamma delta T lymphocytes in both normal human skin and OCL. To determine the extent of junctional diversity in the delta gene of gamma delta T cells in normal human skin and OCL, we sequenced the nucleic acid sequences corresponding to the V delta 2/J delta 1 junctional regions. Sequence analysis of junctional regions demonstrated broad junctional diversity in normal skin but only limited diversity in OCL. Our findings support the hypothesis that skin gamma delta T lymphocytes may derive from a fetal subset of gamma delta T lymphocytes that leaves the thymus early and colonizes the periphery. The limited junctional diversity demonstrated in OCL lesions indicates that gamma delta T cells can undergo oligoclonal expansion following recognition of a specific ligand and supports the idea that junctional regions are important in the recognition of antigenic determinant.

Cellular stress- and transformation-associated cell surface antigens expressed on human and rodent tumor cells

Stress-induced proteins may have significant roles in anti-tumor resistance. To clarify the immunobiological roles of these proteins, we first developed monoclonal antibody (mAb) H1A that detects the HeLa cell-surface antigens whose expression was enhanced by treatment of the cells with physico-chemical stressors, such as heat, H2O2 and tumor necrosis factor. H1A (IgM) detects several molecules with mol. wt. 30, 43, 75, 90, 100, 120 and 150 kDa in Western blot analysis of HeLa cell lysates. Although the antigen was constitutively expressed on the HeLa cell surface, the cell-surface expression of H1A-defined antigen was rapidly enhanced (within 1 h) after heat treatment of HeLa cells. H1A antigens were also transformation-associated, since 1) the activated oncogene-transformed fibroblasts expressed the antigens, but parental nontransformed cells did not, and 2) certain human neoplastic but not normal cells strongly expressed the antigens. Furthermore, H1A mAb also partly blocked the cytotoxicity of purified protein derivatives-stimulated human T cell receptor gamma delta-type T cells towards HeLa cells. Taken together, these data indicate that H1A-defined stress-inducible proteins may play a vital role in anti-tumor resistance by cytotoxic T cells.

Effect of heat shock on susceptibility of normal lymphoblasts and of a heat shock protein 70-defective tumour cell line to cytotoxic T lymphocytes in vitro

The effect of heat shock pretreatment of target cells on their lysability by cytotoxic T lymphocytes was analysed. Killing of Concanavalin A-stimulated normal lymphocytes by minor or major histocompatibility antigen-specific cytotoxic T lymphocytes is unchanged or even slightly enhanced after heat shock, whereas cells of the myeloma line Y3, which is derived from one of the lymphocyte donor strains, become nearly resistant to killing after the same pretreatment. Cold target inhibition experiments show that heat-shocked cells are recognized specifically and that untreated and heat-shocked target cells possess similar inhibitory potential. Y3 cells are unable to express the strongly heat-inducible heat shock protein of 70 kDa (hsp70) after heat shock; the acquired resistance is thus independent of hsp70 induction. Possible mechanisms of the different lysability seen in lymphoblasts and tumour cells after heat shock are discussed.

Characterization of T-cell receptor gamma delta T cells appearing at the early phase of murine Listeria monocytogenes infection

It has been shown that T-cell receptor (TcR) gamma delta + CD4- CD8- T cells increase in number and have an important role in early protection in murine Listeria monocytogenes infection. In this report, to characterize further the phenotype of the gamma delta T cells in listeriosis, we analysed V region gene usage and in vitro antigen recognition of the TcR gamma delta T cells in the peritoneal cavity of mice at the early phase after i.p. infection with a sublethal dose of L. monocytogenes. The gamma delta T cells predominantly expressed V delta 6 which has been reported to be expressed by TcR gamma delta-bearing foetal thymocyte hybridomas specific to mycobacterial and self heat-shock protein (hsp) 60. These early appearing CD3+ CD4- CD8- T cells in Listeria-infected mice, which were reported to be TcR gamma delta T cells, increased in proportion and in size by in vitro stimulation with recombinant hsp 60 from Mycobacterium bovis and purified protein derivative from M. tuberculosis but not by stimulation with heat-killed L. monocytogenes. A 65,000 MW molecule was detected in the lysate of viable L. monocytogenes but not in the lysate of heat-killed L. monocytogenes by a monoclonal antibody (mAb) raised against mycobacterial hsp 60. These results suggest that the V delta 6-bearing peripheral gamma delta T cells are activated by recognizing listerial hsp 60 expressed by viable L. monocytogenes. The hsp 60-reactive V delta 6-bearing T cells may have an important role in protection against L. monocytogenes and other parasites that express hsp 60 at high level.

Characterization of gamma/delta T-lymphocytes in the peripheral blood of patients with active tuberculosis. A comparison with normal subjects and patients with sarcoidosis

Studies in experimental animals have suggested that gamma/delta T-cells play an important role in the immune response against mycobacteria, but evidence for the participation of these cells in the course of human tuberculosis remains fragmentary. We have evaluated the number and state of activation of gamma/delta T-cells in the peripheral blood of patients with active tuberculosis using two-color cytofluorometry, and we have sought evidence that these cells might play a role in the impaired responses to recall antigens seen in some patients by comparing the proliferation of blood T-lymphocytes before and after removing gamma/delta T-cells by panning. Results were compared with those obtained for cells from normal subjects and from patients with sarcoidosis. The proportion and absolute number of circulating CD3+ gamma/delta T-cells were not significantly different comparing blood from patients with tuberculosis and that from control subjects [54.6 +/- 39.9 (n = 17) and 59.1 +/- 30.2 cells/microliters (n = 10), respectively, p > 0.2], and the proportion of cells expressing receptors using the V delta 1 variable region remained unchanged in patients with tuberculosis. Few gamma/delta T-cells from patients with tuberculosis expressed surface antigens associated with activation (IL-2R, < 1%; HLA-DR, 2.6 +/- 3.4%). Four of 15 patients with sarcoidosis had a proportion of gamma/delta T-cells that was outside the range observed in normal subjects, but the absolute number of CD3+ gamma/delta T-lymphocytes was not different comparing the two groups (p > 0.2).(ABSTRACT TRUNCATED AT 250 WORDS)

T cells expressing the gamma delta T-cell receptor potentiate coxsackievirus B3-induced myocarditis

Initial studies determined whether intraperitoneal (i.p.) injection of BALB/c mice with 0.1, 1.0, and 10 mg of adriamycin (a cardiotoxic anthracycline antibiotic) for times ranging between 1 and 9 weeks prior to i.p. injection of 10(5) PFU of coxsackievirus B3 (CVB3) would alter the severity of virus-induced myocarditis. Prior adriamycin exposure enhanced pathogenicity of a poorly pathogenic CVB3 variant (H310A1) but had no effect on myocarditis produced by the pathogenic variant (H3). Cardiac virus concentrations were equivalent in H3- and H310A1-infected mice irrespective of adriamycin treatment. BALB/c mice treated with either 0.1 ml of complete Freund's adjuvant (CFA), 10 mg of adriamycin, or 10(5) PFU of H3 and H310A1 i.p. developed cytolytic Thy 1.2+ lymphocytes (CTL) to H3-infected myocytes 7 days later. CFA-, adriamycin-, and H3-treated mice developed CTL expressing the gamma delta+ T-cell receptors, while H310A1-infected animals did not. Only H3- and H310A1-infected mice developed alpha beta+ CTL. Treatment of BALB/c mice with 0.1 ml of CFA 5 days prior to H310A1 infection dramatically increased myocarditis. Selective depletion of gamma delta+ T cells abrogated this effect. The ability of gamma delta+ T cells to augment the pathogenicity of H310A1 infection was confirmed by adoptive transfer of CFA-stimulated T cells depleted of either gamma delta- or gamma delta+ cells into H310A1-infected recipients.

Mechanisms of augmented resistance of cyclosporin A-treated mice to influenza virus infection by trehalose-6,6'-dimycolate

Cyclosporin A (CsA), which is an immunosuppressive drug of helper T lymphocytes, diminished a resistance of mice to influenza virus infection. Mice inoculated intravenously with trehalose-6,6'-dimycolate (TDM, a glycolipid component of the cell wall of Mycobacterium) in an oil-in-water emulsion (TDM emulsion) recovered the resistance to influenza virus infection impaired by CsA. Number of antibody-producing cells was markedly reduced in CsA- and/or TDM-treated mice. Interferon production in lung of TDM-treated mice was augmented; however, it was extremely reduced not only in CsA-treated mice, but also in CsA- and TDM-treated mice. Activities of natural killer cells of CsA- and/or TDM-treated mice were not different from that of control mice. Numbers of lymphocytes in lung of TDM-treated mice and CsA- and TDM-treated mice were more predominantly increased than that of control mice. Analysis of lung lymphocytes by flow cytometry revealed no difference between the populations of L3T4+ T lymphocytes and Lyt-2.2+ T lymphocytes in CsA- and/or TDM-treated mice and the populations in control mice. However, the population of gamma delta T cell receptor positive (gamma delta TCR+) lymphocytes increased markedly in lung of TDM-treated mice and also CsA- and TDM-treated mice. In vitro experiments showed that macrophage cultures treated with TDM emulsion released a mediator(s) which activates T lymphocytes, but not B lymphocytes. These and our earlier results suggest that the recovered anti-influenza virus resistance of CsA-treated mice by treatment with TDM emulsion was caused by elicitation of macrophages with TDM, then activation of T lymphocytes, especially gamma delta TCR+ lymphocytes.

Evidence for an alpha/beta T cell-independent mechanism of resistance to mycobacteria. Bacillus-Calmette-Guerin causes progressive infection in severe combined immunodeficient mice, but not in nude mice or in mice depleted of CD4+ and CD8+ T cells

Depleting thymectomized mice of CD4+ T cells, or CD4+ plus CD8+ T cells, rendered them incapable of resolving Bacillus-Calmette-Guerin (BCG) infection in their lives, spleens, kidneys, and lungs. However, it did not render them incapable of stabilizing infection in the latter three organs after an initial period of BCG growth. Athymic nude mice showed a similar capacity to control BCG growth in these organs after a certain stage of infection. In contrast, congenitally severe combined immunodeficient (SCID) mice appeared to offer no resistance to BCG infection, in that the organism grew progressively in all organs of these mice and was lethal for them beginning on day 55 of infection. The results suggest that, although CD4+ T cells are important for resolving BCG infection, an alpha/beta T cell-independent mechanism of resistance can be acquired at 2-3 wk of infection that is capable of inhibiting further BCG growth in all organs except the lungs. Because this mechanism is absent from SCID mice, it is likely that it depends on the functions of gamma/delta T cells, B cells, or both types of cells. In keeping with this possibility is the additional finding that SCID mice engrafted with lymph node cells depleted of CD4+ or CD8+ T cells were capable of expressing an appreciable level of resistance against BCG infection.

Stimulation of synovial fluid mononuclear cells with the human 65-kD heat shock protein or with live enterobacteria leads to preferential expansion of TCR-gamma delta+ lymphocytes

T lymphocyte responses to heterologous or self 65-kD heat shock protein (hsp) have been implicated in the pathogenesis of various forms of arthritis. To delineate the relationship of 65-kD hsp to different synovial fluid (SF) T cell subsets, we stimulated synovial fluid (SFMC) and peripheral blood mononuclear cells (PBMC) from patients with different inflammatory rheumatic diseases and from healthy controls with human or mycobacterial 65-kD hsp, tetanus toxoid (TT), heat-killed or live Yersinia enterocolitica. Phenotyping of the resulting T cell lines revealed an increase of up to 97% TCR-gamma delta+ lymphocytes in the 65-kD hsp-stimulated SF-derived lines. This expansion of TCR-gamma delta+ cells was less pronounced with cultures of PBMC. A preferential expansion of TCR-gamma delta+ cells was also shown after SFMC stimulation with live, but not with heat-killed Yersinia or with TT. We conclude that a common mechanism is involved in the selective expansion of TCR-gamma delta+ lymphocytes upon SFMC infection with live Yersinia or upon contact with 65-kD hsp. Out of a panel of TCR-gamma delta+ T lymphocyte clones (TLC) derived from a human 65-kD hsp-stimulated line, only a minority of TLC proliferated weakly upon restimulation with this antigen in the presence of autologous monocytes, whereas TCR-alpha beta+ TLC responded vigorously to the human 65-kD hsp and in some cases also cross-recognized the mycobacterial hsp homologue and/or heat-killed Yersinia. This implies that additional factors or cells may be present in the milieu of SFMC cultures that propagate the expansion of TCR-gamma delta+ cells in response to 65-kD hsp or live bacteria.

T-cell receptor alpha and delta gene assembly in B-cell precursor acute lymphoblastic leukemia

The status of the TCR-alpha/delta genes in B-precursor ALL and the rearrangement patterns of these gene loci are discussed in this review. Although most of these rearrangements have been characterized, some still remain to be clarified. Almost all rearrangements of the TCRs in B-precursor ALL are incomplete and may reflect early recombinational steps during the TCR differentiation processes in normal T-lineage cells. In addition, even in T-cell malignancies, it is rarely possible to obtain clonal cell populations with TCR rearrangements arrested in very early recombinational steps. Therefore, studies of these as yet uncharacterized rearrangements may lead to the discovery of additional gene segments playing important roles in the TCR recombinational processes and may provide useful information for understanding the processes of T-cell differentiation.

T-cell receptor gamma/delta: comparison of gene configurations and function between humans and chimpanzees

The human and chimpanzee T-cell receptor gamma-delta (TCR gamma delta) bearing cells represent a minor subset (3-8%) of T lymphocytes. In the periphery, the TCR gamma delta population has a restricted combinatorial repertoire. The TCRD-V1 and -V2 gene products are expressed in a mutually exclusive fashion, whereas, the TCRD-V2 and the TCRG-V9 encoded proteins show, in general, a coordinated expression. Restriction fragment length polymorphism analysis showed conservation of the restriction sites that identify the TCRG-V9 and TCRD-V2 rearrangements. The human TCRG-V9 locus has two alleles, TCRG-V9A1 and TCRG-V9A2 differing at codon position 31. The chimpanzee TCRG-V9 gene product differs from the products of the human TCRG-V9A1 and TCRG-V9A2 allele by two and three amino acid replacements, respectively. The human and the chimpanzee TCRG-V9-TCRD-V2 lymphocytes show a similar specific proliferative and cytolytic response to human Daudi Burkitt's lymphoma cells. Therefore, the amino acid replacements found in the chimpanzee TCRG-V9 gene product do not change the superantigen specificity across this species barrier.

Reactivity of gamma delta T cells induced by the tumour cell line RPMI 8226: functional heterogeneity of clonal populations and role of GroEL heat shock proteins

The human tumour cell lines RPMI 8226 and Daudi are potent inducers of V gamma 9-expressing T cells. The inducing element of RPMI 8226 has not been defined but evidence suggests that a member of the GroEL heat shock protein (HSP) family (HSP 58) may have a role in the induction by Daudi cells. The present study examined the reactivity patterns of gamma delta T-cell clones generated in response to RPMI 8226 and addressed the possible role of HSP 58 in this process. RPMI 8226 induced a population of V gamma 9 TCR+ cells which were heterogeneous in terms of their cell surface markers, patterns of proliferation and cytotoxic responses. All clones expressed CD3, CD2, CD18 and CD29. They demonstrated variability in expression of CD56, CD8 and HLA-DR. RPMI 8226 stimulated proliferation in purified bulk gamma delta cultures and clones. Daudi was also capable of inducing these cells to proliferate while mycobacterial products were not effective. The clones demonstrated a limited non-MHC-restricted cytotoxicity pattern with some evidence of clonal heterogeneity. Although both Daudi and RPMI 8226 were sensitive to lysis by the clones, cold inhibition experiments indicated differential activity towards these targets. Anti-HSP 58 was inhibitory to gamma delta T-cell induction by RPMI 8226, Daudi and mycobacterial products. However, the anti-HSP 58 antibody appears to bind to the surface of at least six different tumour cell lines with no correlation to their ability to induce gamma delta T cells and the anti-HSP 58 inhibited non-gamma delta responses.

Intraepithelial gamma delta T-cell-receptor lymphocytes and genetic susceptibility to coeliac disease

Although the proportion of gamma delta T-cell-receptor (TCR)-bearing intraepithelial lymphocytes is increased in the jejunum of patients with active coeliac disease, an abnormality thought to be specific among those with gluten-sensitive enteropathy, the factors influencing gamma delta TCR expression remain uncertain. We examined the relation between genetic factors associated with coeliac disease and intraepithelial gamma delta T lymphocyte distribution in both coeliac patients and their healthy first-degree relatives. 41% (45/109) of healthy relatives had an increased density of gamma delta T cells in their mucosa and 66% had an increased density of alpha beta T cells. By contrast with alpha beta T cells, the density of gamma delta cells was significantly associated with genetic markers for coeliac disease susceptibility (DR3, DQA, and DQB). We also found a dose effect of DQA and DQB genes on the number of intraepithelial gamma delta T cells. An increased density of gamma delta T cells in normal jejunal mucosa of a healthy individual with appropriate genetic determinants might be necessary for the development of the typical lesions of coeliac disease. Routine jejunal histological studies should include gamma delta T-cell counts, thus allowing early detection of coeliac disease latency.

Heat shock proteins in health and disease

Heat shock proteins are among the most abundant proteins of the biosphere. They not only play a major role under stress conditions but also perform important physiological functions. The present review summarizes the potential contribution of heat shock proteins to health and disease related to immunity: their contribution to antibody assembly and antigen presentation; their role in host cell protection against "immune stress"; their participation in tumor surveillance; their relation to gamma/delta T-cell recognition; their function as microbial virulence factors; their dominant antigenicity for the immune response against microbial pathogens; and their possible role as autoantigens. The findings summarized here illustrate the marked liaison between heat shock proteins and the immune response, which may be both beneficial and detrimental to the host.