A monoclonal antibody specific for a common determinant of the human T cell receptor gamma/delta directly activates CD3+WT31- lymphocytes to express their functional program(s)

Zoledronate Triggers Vδ2 T Cells to Destroy and Kill Spheroids of Colon Carcinoma: Quantitative Image Analysis of Three-Dimensional Cultures

New successful anti-cancer strategies are based on the stimulation of immune reaction against tumors: however, preclinical testing of such treatments is still a challenge. To improve the screening of anti-cancer drugs, three-dimensional (3D) culture systems, including spheroids, have been validated as preclinical models. We propose the spheroid 3D system to test anti-tumor drug-induced immune responses. We show that colorectal carcinoma (CRC) spheroids, generated with the epithelial growth factor (EGF), can be co-cultured with Vδ2 T cells to evaluate the anti-tumor activity of these effector lymphocytes. By computerized image analysis, the precise and unbiased measure of perimeters and areas of tumor spheroids is achievable, beside the calculation of their volume. CRC spheroid size is related to ATP content and cell number, as parameters for cell metabolism and proliferation; in turn, crystal violet staining can check the viability of cells inside the spheroids to detect tumor killing by Vδ2 T cells. In this 3D cultures, we tested (a) zoledronate that is known to activate Vδ2 T cells and (b) the therapeutic anti-EGF receptor humanized antibody cetuximab that can elicit the antibody-dependent cytotoxicity of tumor cells by effector lymphocytes. Zoledronate triggers Vδ2 T cells to kill and degrade CRC spheroids; we detected the T-cell receptor dependency of zoledronate effect, conceivably due to the recognition of phosphoantigens produced as a drug effect on target cell metabolism. In addition, cetuximab triggered Vδ2 T lymphocytes to exert the antibody-dependent cellular cytotoxicity of CRC spheroids. Finally, the system reveals differences in the sensitivity of CRC cell lines to the action of Vδ2 T lymphocytes and in the efficiency of anti-tumor effectors from distinct donors. A limitation of this model is the absence of cells, including fibroblasts, that compose tumor microenvironment and influence drug response. Nevertheless, the system can be improved by setting mixed spheroids, made of stromal and cancer cells. We conclude that this type of spheroid 3D culture is a feasible and reliable system to evaluate and measure anti-tumor drug-induced immune responses beside direct anti-cancer drug effect.

Identification of guinea pig gammadelta T cells and characterization during pulmonary tuberculosis

Guinea pigs are an alternative small animal model for many disease studies. Here we describe a pan-gammadelta monoclonal antibody (anti-TCRdelta1) specific for the constant region of human T cell receptor delta chains that cross-reacts with a subpopulation of guinea pig (Cavia porcellus) lymphocytes. The phenotype and distribution of this subpopulation is consistent with the guinea pig gammadelta T cell subset. FACS analysis of fresh PBMC and splenocytes from naïve guinea pigs revealed the presence of a subset of cells that stained with the anti-TCRdelta1 mAb. The relative percentage of anti-TCRdelta1 positive cells in PBMC and tissues is similar to that described for gammadelta T cells in other species. Immunohistochemistry of tissues also revealed a distribution of anti-TCRdelta1 positive cells consistent with gammadelta T cells. These data are further supported by staining of a polyclonal guinea pig T cell line that became progressively CD4 and CD8 negative in long-term culture. Analysis of PBMC from guinea pigs following aerosol infection with virulent Mycobacterium tuberculosis revealed no apparent changes in the steady-state percentage of blood gammadelta+ T cells. Taken together, these data suggest that the anti-TCRdelta1 antibody recognizes the gammadelta T cell subset in guinea pigs. This reagent may be useful for examining gammadelta T cells in various disease models where the guinea pig is a more desirable model for study.

Effect Of Human Natural Killer and γδ T Cells on the Growth of Human Autologous Melanoma Xenografts in SCID Mice

Natural killer (NK) cells were first identified for their ability to kill tumor cells of different origin in vitro. Similarly, gammadelta T lymphocytes display strong cytotoxic activity against various tumor cell lines. However, the ability of both the NK and gammadelta cells to mediate natural immune response against human malignant tumors in vivo is still poorly defined. Severe combined immunodeficient (SCID) mice have been successfully engrafted with human tumors. In this study, the antitumor effect of local as well as of systemic treatments based on NK cells or Vdelta1 or Vdelta2 gamma/delta T lymphocytes against autologous melanoma cells was investigated in vivo. The results show that all three of the populations were effective in preventing growth of autologous human melanomas when both tumor and lymphoid cells were s.c. inoculated at the same site. However, when lymphoid cells were infused i.v., only NK cells and Vdelta1 gamma/delta T lymphocytes could either prevent or inhibit the s.c. growth of autologous melanoma. Accordingly, both NK cells and Vdelta1 gammadelta T lymphocytes could be detected at the s.c. tumor site. In contrast, Vdelta2 gammadelta T lymphocytes were only detectable in the spleen of the SCID mice. Moreover, NK cells maintained their inhibitory effect on tumor growth even after discontinuation of the treatment. Indeed they were present at the tumor site for a longer period. These data support the possibility to exploit NK cells and Vdelta1 gammadelta T lymphocytes in tumor immunotherapy. Moreover, our study emphasizes the usefulness of human tumor/SCID mouse models for preclinical evaluation of immunotherapy protocols against human tumors.

Conservation of nonpeptide antigen recognition by rhesus monkey V gamma 2V delta 2 T cells

We have previously found that monkey Vgamma2Vdelta2(+) T cells mount adaptive immune responses in response to Mycobacterium bovis bacillus Calmette-Guérin infections. We have now analyzed rhesus monkey gammadelta T cell responses to nonpeptide Ags and superantigens. Like human Vgamma2Vdelta2(+) T cells, rhesus monkey gammadelta T cells are stimulated when exposed to prenyl pyrophosphate, bisphosphonate, and alkylamine Ags. Responsiveness was limited to gammadelta T cells expressing Vgamma2Vdelta2 TCRs. Rhesus monkey Vgamma2Vdelta2(+) T cells also responded to the superantigen, staphyloccocal enterotoxin A. Sequencing of the rhesus monkey Vgamma2Vdelta2 TCR revealed a strong sequence homology to human Vgamma2Vdelta2 TCR that preserves important sequence motifs. Moreover, chimeric TCRs that pair human Vgamma2 with monkey Vdelta2 and monkey Vgamma2 with human Vdelta2 retain reactivity to nonpeptide Ags and B cell lymphomas. A molecular model of the rhesus monkey Vgamma2Vdelta2 TCR has a basic region in the complementarity-determining region 3 binding groove that is similar to that seen in the human Vgamma2Vdelta2 TCR and preserves the topology of the complementarity-determining region loops. Thus, recognition of nonpeptide prenyl pyrophosphate, bisphosphonate, and alkylamine Ags is conserved in primates suggesting that primates can provide an animal model for human gammadelta T cell Ag responses.

Expansion of unconventional T cells with natural killer markers in malaria patients

Immunological states during human malarial infection were examined. In parallel with parasitemia and anemia, granulocytosis was induced in the blood of patients, especially those infected with Plasmodium (P.) falciparum. At that time, the level of lymphocytes remained unchanged or slightly increased in the blood. However, the distribution of lymphocyte subsets was modulated, showing that the proportion of CD56(+)T cells, CD57(+)T cells, and gammadeltaT cells (i.e. all unconventional T cells) had increased in patients infected with P. falciparum or P. vivax. This phenomenon occurred at the early phase of infection and disappeared in the course of recovery. The data from patients with multiple attacks of P. vivax infection showed that there was no augmentation of these responses. In adult cases, the increase in the proportion of unconventional T cells seemed to closely parallel disease severity. However, all these responses were weak in children, even those infected with P. falciparum. In conjunction with accumulating evidence from mouse malaria experiments, the present results suggest that the immunological state induced by malarial infection might mainly be an event of unconventional T cells and that the immunological memory might not be long-lasting, possibly due to the properties of unconventional T cells.

Diagnostic role of tests for T cell receptor (TCR) genes

Rapid advances in molecular biological techniques have made it possible to study disease pathogenesis at a genomic level. T cell receptor (TCR) gene rearrangement is an important event in T cell ontogeny that enables T cells to recognise antigens specifically, and any dysregulation in this complex yet highly regulated process may result in disease. Using techniques such as Southern blot hybridisation, polymerase chain reaction, and flow cytometry it has been possible to characterise T cell proliferations in malignancy and in diseases where T cells have been implicated in the pathogenesis. The main aim of this article is to discuss briefly the process of TCR gene rearrangement and highlight the disorders in which expansions or clonal proliferations of T cells have been recognised. It will also describe various methods that are currently used to study T cell populations in body fluids and tissue, their diagnostic role, and current limitations of the methodology.

gammadelta T-cell lymphomas: a homogeneous entity?

gammadelta T-cells comprise an immunologically distinct lymphoid population, characterized by specific morphological, phenotypical and functional properties. Therefore it seems reasonable to speculate that neoplasms derived from this particular T-cell subset display distinct features. Indeed, the prototype gammadelta T-cell lymphoma, hepatosplenic T-cell lymphoma constitutes a unique clinicopathological entitity which is intimately associated with a gammadelta T-cell phenotype. However, gammadelta T-cell lymphomas have also been described in other extranodal sites where, unlike reactive gammadelta T-cells and hepatosplenic gammadelta T-cell lymphomas, they display an important morphological heterogeneity. Moreover, these nonhepatosplenic gammadelta T-cell lymphomas are essentially not that different from their alphabeta T-cell receptor for antigen (TCR)-expressing counterparts and thus may be incorporated in the established T-cell lymphoma subclasses. However, subtle differences regarding their histopathological appearance as well as their biological behaviour indicate that further studies to determine the exact significance of TCR expression are required. Such inquiries may contribute to the general understanding of T-cell lymphomagenesis in general, which is still obscure.

Human gamma delta T cells recognize heat shock protein-60 on oral tumor cells

In the present investigations, gammadelta T cells were isolated from the peripheral blood of oral cancer patients and analyzed for their immunophenotype and cytotoxic potential. Flow-cytometric analysis revealed a dominant population expressing Vgamma9 and Vdelta2 T-cell receptors. In a 4-hr 51Cr-release assay, activated gammadelta T cells showed specific cytotoxicity against Daudi Burkitt's lymphoma cells and fresh oral tumor cells. Cold target competition assays demonstrated that gammadelta T cells recognize a common ligand on Daudi and oral tumor cells. Expression of heat shock protein 60 (hsp60) molecules was detected on the surface of Daudi as well as oral tumor cells by flow cytometry and immunoprecipitation of surface biotinylated cells by anti-hsp60 monoclonal antibody (MAb). Such MAbs brought about a significant inhibition of cytotoxicity of gammadelta T cells against Daudi and oral tumor cells. The results suggest that gammadelta T cells isolated from the peripheral blood of oral cancer patients have the ability to lyse oral tumor cells. The lysis of oral tumor cells occurs via recognition of hsp60 on the surface of oral tumor cells.

Duodenal intraepithelial and lamina propria T lymphocytes in human immunodeficiency virus-infected patients with and without diarrhoea

BACKGROUND

Diarrhoea is an important problem in human immunodeficiency virus (HIV)-infected patients. Intestinal pathologic conditions may arise from changes in local immunocyte populations. The aims of our study were to establish the histologic features of the duodenal mucosa of HIV-infected patients and to determine a) the phenotype of small-intestinal-intraepithelial (IELs) and lamina propria (LPLs)-lymphocytes; b) their degree of activation and differentiation within the lamina propria; and c) their relation to the presence of diarrhoea.

METHODS

Distal duodenal biopsy specimens were obtained prospectively from 29 HIV-infected patients-11 patients with diarrhoea (group 1) and 18 patients without diarrhoea (group 2)- and from 42 patients who had neither any risk factor for HIV nor diarrhoea (group 3). Histopathologic and immunohistochemical studies were combined with flow cytometric analysis, after separation of the mucosal intraepithelial compartment from the lamina propria.

RESULTS

The median number of IELs and the percentage of gamma delta IELs were both unchanged in HIV-infected patients as compared with controls. In HIV-infected patients LP CD4 cells were decreased, and LP CD8 cells increased. No significant difference was found in the expression of CD25 or CD27 within the LP CD8 populations of HIV-infected patients in groups 1 and 2.

CONCLUSIONS

These findings suggest that the occurrence of diarrhoea in HIV-infected patients is unrelated to IEL and LPL phenotype.

Human intestinal Vdelta1+ lymphocytes recognize tumor cells of epithelial origin

gammadelta T cells can be grouped into discrete subsets based upon their expression of T cell receptor (TCR) variable (V) region families, their tissue distribution, and their specificity. Vdelta2+ T cells constitute the majority of gammadelta T cells in peripheral blood whereas Vdelta1+T cells reside preferentially in skin epithelium and in the intestine. gammadelta T cells are envisioned as first line host defense mechanisms capable of providing a source of immune effector T cells and immunomodulating cytokines such as interleukin (IL) 4 or interferon (IFN) gamma. We describe here the fine specificity of three distinct gammadelta+ tumor-infiltrating lymphocytes (TIL) obtained from patients with primary or metastatic colorectal cancer, that could be readily expanded in vitro in the presence of IL-1beta and IL-7. Irrespective of donor, these individual gammadelta T cells exhibited a similar pattern of reactivity defined by recognition of autologous and allogeneic colorectal cancer cells, renal cell cancer, pancreatic cancer, and a freshly isolated explant from human intestine as measured by cytolytic T cell responses and by IFN-gamma release. In contrast, tumors of alternate histologies were not lysed, including lung cancer, squamous cell cancer, as well as the natural/lymphocyte-activated killer cell-sensitive hematopoietic cell lines T2, C1R, or Daudi. The cell line K562 was only poorly lysed when compared with colorectal cancer targets. Target cell reactivity mediated by Vdelta1+ T cells was partially blocked with Abs directed against the TCR, the beta2 or beta7 integrin chains, or fibronectin receptor. Marker analysis using flow cytometry revealed that all three gammadelta T cell lines exhibit a similar phenotype. Analysis of the gammadelta TCR junctional suggested exclusive usage of the Vdelta1/Ddelta3/Jdelta1 TCR segments with extensive (< or = 29 bp) N/P region diversity. T cell recognition of target cells did not appear to be a major histocompatibility complex restricted or to be correlated with target cell expression of heat-shock proteins. Based on the ability of some epithelial tumors, including colorectal, pancreatic, and renal cell cancers to effectively cold target inhibit the lysis of colorectal cancer cell lines by these Vdelta1+ T cell lines, we suggest that intestinal Vdelta1+ T cell lines, we suggest that intestinal Vdelta1+ T cells are capable of recognizing cell surface Ag(s) shared by tumors of epithelial origin.

An immunohistochemical study of immunological phenomena in minor salivary glands in patients with Sjögren's syndrome

Using different monoclonal antibodies, we performed an immunofluorescent technique on labial salivary glands in order to investigate the immunological phenomena involved in Sjögren's syndrome (SS). An aberrant expression of HLA-DR molecules was detected on cytoplasm of epithelial labial salivary cells in 9 out of 19 (47%) patients, with SS. No such expression was found in 8 patients without SS or in 3 normal controls. HLA-DQ molecules were demonstrated also in two out of ten SS patients without HLA-DR. A lymphocytic infiltration was not correlated with the expression of class II molecules. T cells bearing gamma delta receptors were not detected. The intracellular adhesion molecules (ICAM-1) and lymphocyte function associated antigen-1 (LFA-1) were not found on epithelial glandular salivary cells of patients and controls. In conclusion, these data suggested that the absence of ICAM-1 and LFA-1 in salivary cells and the absence of infiltrating T cells bearing gamma delta receptors exclude their immunopathogenetic role in SS; moreover, these data demonstrated that the aberrant expression of HLA class II molecules on epithelial salivary cells of patients with SS is not a phenomenon correlated with the lymphocytic infiltration.

Infiltrating gamma/delta T-cell receptor-positive lymphocytes in Hashimoto's thyroiditis, Graves' disease and papillary thyroid cancer

In the present study we have evaluated the expression of different molecular forms of the antigen receptor (TcR) on lymphocytes derived from thyroid tissue of patients with Graves' disease, Hashimoto thyroiditis and papillary cancer both in situ by APAAP technique and on isolated lymphocytes by indirect immunofluorescence. A panel of monoclonal antibodies (mAbs) recognizing alpha/beta and gamma/delta TcR-positive subsets was used. The results showed that the large majority of T-cells in thyroid infiltrates were alpha/beta TcR+, gamma/delta TcR+ ones being very rare or nearly absent, whatever the disease (autoimmune or neoplastic). No difference between gamma/delta TcR+ T-cell subsets (V delta 1+ or V delta 2+) was observed. Thus, neither in autoimmune thyroid diseases nor in papillary cancer gamma/delta TcR+ cells are likely to be a major effector-T cell population.

p40, a novel surface molecule involved in the regulation of the non-major histocompatibility complex-restricted cytolytic activity in humans

Four monoclonal antibodies (mAb) termed NKTA255, NKTA72, 1F1 and 1B1 were selected on the basis of their ability to inhibit the cytolytic activity of natural killer (NK) cell clones against P815 target cells. These mAb selectively reacted with normal or tumor cells of hematopoietic origin and displayed a cellular distribution similar to that of CD45 or CD11a/CD18 antigens. Immunoprecipitation experiments showed that they reacted with molecules with an apparent molecular mass of 40 kDa under both reducing and nonreducing conditions ("p40" molecules), thus differing from CD45 or CD11a/CD18 antigens as well as from the "inhibitory" receptors for HLA class I molecules (i.e. p58, CD94 and NKB1 molecules). Double-immunofluorescence analysis of peripheral blood mononuclear cells allowed the identification of three distinct populations on the basis of the fluorescence intensity of cells stained with anti-p40 mAb. p40bright cells were homogeneously HLA-DR-positive, p40medium cells were HLA-DR-negative but co-expressed CD56 antigens, while p40dull cells were all CD3+. Anti-p40 mAb strongly inhibited the lysis of K562 target cells, mediated by fresh NK cells, as well as the lysis of P815 target cells by NK or T cell clones. In addition, in redirected killing assays, anti-p40 mAb strongly reduced the anti-CD16 mAb-induced cytolytic activity of NK cell clones. On the contrary, they did not inhibit either the anti-CD3 or anti-T cell receptor mAb-mediated cytolytic activity of T cell clones or the lysis of allogeneic phytohemagglutinin blasts mediated by specific cytolytic T cell clones. The p40-induced inhibition of the NK cytotoxicity required optimal cross-linking, as anti-p40 mAb could inhibit the lysis of Fc gamma receptor (Fc gamma R)-positive but not of Fc gamma R-negative target cells. In addition, (Fab')2 fragments of anti-p40 mAb failed to inhibit the lysis of Fc gamma R-positive target cells. In conclusion, p40 molecules represent a new type of inhibitory surface molecule that appears to play a general regulatory role in the NK-mediated cytolysis.

Characterization of a cyclosporin A-sensitive activation pathway in cultured T and natural killer cells

Previously, the authors have described a molecule, identified by the LD6 monoclonal antibody (MoAb), present at the cell surface of long-term cultured T and Natural Killer (NK) cells which is involved in cell triggering. In the study described here the authors used biotin surface labelling and immunoprecipitation to show that LD6 MoAb recognizes a surface protein of approximately 65 kDa. In combination with submitogenic concentrations of phorbol esters (PMA); LD6 MoAb was able to induce accumulation of mRNA specific for GM-CSF, gamma-IFN and TNF-alpha and release of these cytokines by LD6+ T-cell lines. Both lymphokine production and lymphokine-specific mRNA accumulation induced by the LD6 MoAb were blocked totally by Cyclosporin A (CsA). To investigate the mechanism(s) of signal transduction through this activatory pathway, the authors performed Ca++ mobilization experiments. The results of these experiments suggested a role for Ca++ in signal transduction. The Ca++ mobilization induced by LD6 MoAb cross-linking could be inhibited totally by the use of pertussis toxin, indicating a possible role for G proteins in signalling through the LD6 MoAb-reactive molecule. Western blot analysis performed with an anti-phosphotyrosine antibody did not suggest that tyrosine kinase activation has a role.

Self class I molecules protect normal cells from lysis mediated by autologous natural killer cells

The surface expression of given HLA class I alleles protects target cells from lysis mediated by natural killer (NK) clones specific for these (or related) alleles. We could define two groups of NK clones specifically recognizing either Cw4 and related C alleles ("group 1") or Cw3 and related C alleles ("group 2"), respectively. Monoclonal antibodies (mAb) to class I molecules should interfere with the interaction between NK receptors and class I molecules, thus resulting in lysis of protected target cells. However, none of the numerous available mAb to class I molecules had this effect. Therefore, we attempted to select new mAb on the basis of their ability to induce lysis of Cw4- or Cw3-protected lymphoblastoid cell lines by "group 1" or "group 2" NK clones, respectively. From mice immunized with phytohemagglutinin (PHA)-activated lymphocytes expressing either Cw3 or Cw4 alleles, two mAb were selected, the 6A4 (IgG1) and the A6-136 (IgM), on the basis of their ability to induce lysis of protected target cell. Both mAb immunoprecipitated molecules which, in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gave two bands of 45 and 12 kDa, typical of the class I heavy chain and beta 2 microglobulin, respectively. It has been proposed (but not proven), that self major histocompatibility complex class I molecules protect normal cells from autologous NK cell lysis. Thus, we used the 6A4 and A6-136 mAb to assess this possibility directly. Cw4-specific ("group 1") and Cw3-specific ("group 2") NK clones were isolated from donors expressing the corresponding (or related) protective C alleles. None of these clones lysed autologous PHA-induced blasts, used as target cells. However, addition of the F(ab')2 of 6A4 mAb or the A6-136 mAb resulted in lysis of autologous target cells by "group 1" or "group 2" NK clones, respectively. These data provide direct evidence that the expression of class I molecules protects normal cells from lysis by autologous NK cells.

Targeting of T lymphocytes against EGF-receptor+ tumor cells by bispecific monoclonal antibodies: requirement of CD3 molecule cross-linking for T-cell activation

Targeting of T lymphocytes against epidermal growth-factor-receptor (EGF-R)+ tumor cells was achieved by constructing a hybrid hybridoma which secretes an anti-EGF-R/anti-CD3 bispecific monoclonal antibody (biMAb) of hybrid isotype (IgG1/IgG2a). Purification of biMAb molecules from parental anti-EGF-R and anti-CD3 MAbs was performed by protein-A chromatography. The purified biMAb was able to trigger the lysis of EGF-R+ tumor cell lines (A431, IGROV-1, MDA-468 and U-87) and of NIH-3T3 transfectants expressing human EGF-R by cytolytic T lymphocytes, but it was ineffective in the case of EGF-R-negative tumor targets. Normal EGF-R+ cells (keratinocytes and endometrial cells) were also susceptible to biMAb-targeted cytolysis. However, the amount of biMAb required to induce half-maximal cytolysis of tumor cells over-expressing the EGF-R molecule (A431) was considerably lower than that required to induce lysis of EGF-R+ tumor or normal cells which express EGF-R at considerably lower density. The ability of such biMAbs to deliver activation signals to T cells was evaluated by Ca++ mobilization and lymphokine production experiments. The soluble anti-EGF-R/anti-CD3 biMAb failed to induce intracellular Ca++ increases, which occurred only after cross-linking induced by an anti-mouse IgG antibody. Secretion of lymphokines (IFN-gamma, TNF-alpha and GM-CSF) was induced by contact of the biMAb-coated effector cells with the relevant tumor target, whereas the soluble biMAb was virtually ineffective. In addition, biMAb-coated effector cells retained the ability to recognize and to lyse EGF-R+ tumor cells for a prolonged period of time. Our data indicate that activation of effector cells targeted by biMAbs can only occur at the tumor site, where cross-linking of surface CD3 molecules is induced by contact with the tumor cells.

Increase in T cells bearing the gamma/delta receptor associated with lymphoproliferative disease of granular lymphocytes in an infant with intractable diarrhea

A two-year-old infant with intractable diarrhea and lymphoproliferative disease of granular lymphocytes attributed to a persistent cytomegalovirus infection showed an increase in cells bearing the gamma/delta T-cell receptor (TCR), which accounted for approximately 20% of total peripheral blood lymphocytes and 40% of CD3+ T cells. Of the gamma/delta TCR+ cells, two-thirds were double negative (CD4-/CD8-) and the other one-third CD8 positive. The majority of gamma/delta+ cells were delta TCS 1 positive. The predominance of delta TCS 1 positive cells was also confirmed on biopsy of lymphoid tissues from the colon. After improvement of watery diarrhea and malnutrition following three-month hyperalimentation, the number of gamma/delta TCR+ cells decreased. The patient subsequently died of pneumonia at the age of 2 years and 11 months. A possible site-specific role for the gamma/delta TCR+ cells, particularly delta TCS 1+ cells, in the human intestine is discussed.

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.

Human CD3-CD16+ natural killer cells express the hGATA-3 T cell transcription factor and an unrearranged 2.3-kb TcR delta transcript

In this study we analyzed the T cell receptor(TcR) delta transcripts expressed by CD3-CD16+ cells and we investigated whether these cells expressed the hGATA-3 T cell transcription factor and the recombination-activating gene (RAG)-1. Multiple TcR delta transcripts deriving from an unrearranged TcR delta gene were detected in both polyclonal and clonal CD3-CD16+ natural killer(NK) cell lines. Two unrearranged TcR delta transcripts had a size similar to that of the functional TcR delta mRNA (2.3 and 1.3 kb) found in TcR gamma/delta+ T lymphocytes. Sequence analysis of nine different 2.3-kb cDNA clones obtained from NK-derived polyA+ RNA confirmed that they corresponded to an unrearranged TcR delta gene. These cDNA were 2343 bp long and their transcription initiation site was located 814 bp upstream from the J delta 1 segment. The sequence located upstream of the J delta 1 segment corresponded to the previously reported germ-line sequence. The J delta 1 segment was correctly spliced to C delta; in addition the four C delta exons were found to be already assembled. Two polyadenylation sites were present in the fourth C delta exon. However, only that located at the 3' end appeared to be utilized in the 2.3-kb cDNA. The expression of hGATA-3, a T cell-specific factor known to be involved in the regulation of the transcription of TcR delta locus, was analyzed by Northern blot, in cultured NK cell population and clones (but not in freshly derived cell populations). All NK clones and cell lines studied were found to express hGATA-3-specific mRNA, suggesting that hGATA-3 may be involved in the regulation of the unrearranged TcR delta gene expression in NK cells. Finally, no transcription of the RAG-1 gene could be detected in all NK cell lines or clones analyzed.

Coexpression of Fc gamma receptor IIIA and interleukin-2 receptor beta chain by a subset of human CD3+/CD8+/CD11b+ lymphocytes

In this study we identify and characterize a subset of human peripheral blood T cells, present in all individuals, that has features previously described for T cells either separately or in special circumstances. These cells are found in purified suspensions of resting peripheral blood lymphocytes within the CD8+ T lymphocytes, express alpha beta T cell receptor (TCR), and can be identified and isolated because of high-density expression of surface CD11b (TCR alpha beta +/CD3+/CD8+/CD11b+ cells). They coexpress constitutively the IL-2 receptor beta chain, Fc gamma RIIIA, and CD56. Although they do not mediate spontaneous cytotoxicity, CD3+/CD8+/CD11b+ cells have cytotoxic potential, demonstrated in redirected cytotoxicity assays with P815 target cells in the presence of anti-Fc gamma RIII (CD16) or anti-CD3 monoclonal antibodies. Stimulation of CD3+/CD8+/CD11b+ cells with rIL-2 induces proliferation, cytotoxicity against NK-sensitive and NK-resistant target cells, and expression of surface activation antigens, including IL-2 receptor alpha chain (CD25). CD3+/CD8+/CD16+/CD56+ cell clones with cytotoxic functions including those mediated by engagement of surface CD16 were obtained by limiting-dilution cloning of purified CD3+/CD8+/CD11b+ cells in the presence of rIL-2 and autologous feeder cells. Our data support the hypothesis that the CD3+/CD8+/CD11b+/CD16+ cells represent a discrete peripheral blood lymphocyte subset that could be the physiological counterpart of that expanded in several pathological conditions and in large granular lymphocyte lymphocytosis.

Clonal expansions of activated gamma/delta T cells in recent-onset multiple sclerosis

Multiple sclerosis (MS) is a chronic disease characterized by focal demyelination of the white matter of the brain and spinal cord. Central nervous system damage appears to be mediated by infiltrating T lymphocytes and macrophages, and a central role for autoreactive CD4+ T cells has been proposed. However, the initial immune events that lead to the chronic process of MS remain unidentified. We now present evidence that a subset of T lymphocytes bearing gamma/delta T-cell antigen receptors has been activated in patients with recent-onset disease. Cells recovered from the cerebrospinal fluid of subjects with MS were cultured for short periods of time in medium supplemented with T-cell growth factors. Expansions of V delta 1 and V delta 2 T-cell receptor-bearing lymphocytes were found only in cell populations obtained from subjects with recent-onset disease. Similar populations were not expanded in subjects with chronic MS or other neurological diseases. Junctional region sequencing showed the expanded gamma/delta T cells to be oligoclonal in nature, suggestive of specific stimulation by antigen. These results reveal a fundamental difference in the immunopathogenesis of acute vs. chronic disease and provide additional insight into the autoimmune nature of MS.

Accumulation of gamma delta T cells in chronic cutaneous lupus erythematosus

Monoclonal antibodies (moAbs) that recognize common or variable determinants of the gamma delta T-cell receptor (TcR) were used to assess gamma delta T-cell distribution on biopsy specimens and/or peripheral blood leukocytes (PBL) from 30 patients suffering from chronic cutaneous lupus erythematosus (CCLE). CD3+/gamma delta TcR + T cells were evaluated in 15 biopsies from patients with CCLE lesions, their numbers varying from 0.5 to 15.0% of all intralesional CD3 +T cells present. In all specimens from lesional skin gamma delta TCR+T cells were BB3 + and/or Ti gamma A +, indicating predominant use of the V gamma 2/V delta 2 phenotype. In the CCLE lesions the intraepidermal V gamma 2/V delta +T cells were observed in close vicinity to the damaged basal keratinocyte (KC) layer, and also randomly scattered among the densely packed inflammatory infiltrate in the dermis. In contrast to the immunohistologic findings, no numerical increase of gamma delta TcR+T cells could be observed among PBL from 28 of 30 CCLE patients. Only one CCLE patient being treated with hydroxychloroquine for two months had 15% CD3 +/gamma delta TcR+T cells among the PBL. Based on the immunohistologic findings one may infer that in CCLE, a skin-restricted form of LE, V gamma 2/V delta 2 +T cells expand extrathymically to an as yet unknown stimulus. One may also propose that these gamma delta T cells--based on their cytotoxic capacity--may contribute to the epidermal damage. It remains to be determined whether the extrathymic expansion of V gamma 2/V delta 2 +Tells occurs within lesional skin or in the periphery within subsequent recruitment into skin lesions. The results obtained by fluorescence-activated cell sorter analysis favor the first possibility.

Clonal expansion of lung V delta 1+ T cells in pulmonary sarcoidosis

Sarcoidosis is a multisystem disease of unknown etiology characterized by the presence of noncaseating granulomas in involved tissues. To investigate a potential role for gamma/delta T cells in the pathogenesis of pulmonary sarcoidosis, we studied lung and blood T cells from patients for preferential expression of particular gamma/delta T cell receptors. An abnormally high percentage of gamma/delta cells was found in the blood of some patients. However, the increased percentage did not reflect an increase in absolute number, and appeared to be secondary to a decrease in T cells expressing alpha/beta receptors. Furthermore, as in normals, the circulating gamma/delta cells in patients predominantly expressed V gamma 9/V delta 2 receptors, a subset that was not enriched at the site of disease. In contrast, in the lung, an increased percentage of gamma/delta cells expressing V delta 1 was found in a subset of patients. Importantly, these cells demonstrated evidence of prior activation by selectively expanding in vitro in the presence of interleukin 2. Furthermore, an analysis of junctional region sequences revealed their clonal nature. These clonal expansions of V delta 1+ cells in pulmonary sarcoidosis provide evidence for a disease process that involves specific recognition of a local antigen by T cells, and contributes new information regarding the nature of the as yet undefined antigenic stimulus.

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.

The skin in severe combined immunodeficiency: a case with transient cutaneous presence of gamma/delta (TRC1+) T cells

We report the case of a boy with severe combined immunodeficiency (SCID) and serious skin problems. The level of purine 5'-nucleotidase was greatly reduced in the lymphocytes of this patient. To our knowledge, no patients with SCID and this enzyme deficiency have been described previously. The relationship between reduced levels of this enzyme and the immunodeficiency is unclear. This case is also unusual because of the presence of large numbers of T lymphocytes expressing TCR1 (gamma/delta) in the skin. Moreover, the presence of so many TCR1-positive cells was not consistent with the low numbers of these cells in the peripheral blood. These cells were not present in skin biopsies taken at a later stage during the course of the disease. An oligoclonal lymphocytosis developed during follow-up, and a monoclonal antibody reactive with these clones was found, indicating that these lymphocytes were present in the skin. This case report illustrates the benefit of the use of monoclonal antibodies in identifying the cells involved in the cutaneous inflammation in SCID, in order to gain a better insight into the characteristics of these cells.

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.

Functional and morphologic characterization of human T lymphocytes expressing the TCR gamma/delta

A minor subset of T lymphocytes express a TCR composed of gamma and delta chains. This subset differs from conventional T cells for a number of phenotypic and functional characteristics. TCR gamma/delta+ cells simultaneously lack both CD4 and CD8 antigens. Cloning of CD4-8- peripheral blood lymphocytes, under limiting dilution conditions, revealed that they are homogeneously composed of cytolytic cells which efficiently lyse tumor target cells. Formal proofs have been provided that TCR gamma/delta+ cells are able to recognize antigens. For example, they proliferated in response to allogeneic mixed lymphocyte culture (MLC); in addition, MLC-derived TCR gamma/delta+ cells specifically lysed PHA-induced blast cells bearing the stimulating alloantigens. The selection of monoclonal antibodies specific for TCR gamma/delta molecules allowed to identify two distinct subsets of TCR gamma/delta+ cells. Both of these mABs, termed BB3 and delta TCS-1 respectively, induced specific activation of cloned cells expressing the corresponding antigenic determinants (as assessed by measurements of intracellular Ca++ and/or lymphokine production or cytolytic activity). Analysis of the distribution of subsets expressing different forms of TCR gamma/delta, showed that the BB3-reactive form is prevalent in the peripheral blood. In contrast, delta-TCS-1-reactive cells are relatively infrequent in peripheral blood but represent the majority of TCR gamma/delta+ cells in tissues.

Predominant expansion of V gamma 9/V delta 2 T cells in a tularemia patient

We describe a 58-year-old man with tularemia and expanding gamma delta T cells in his peripheral blood lymphocytes (PBL) (32.7% of total PBL). In the present work, we analyzed the T-cell receptor V gamma/V delta repertoire of these cells by making use of the polymerase chain reaction and flow cytometry and found that they were mostly CD4- CD8- CD3+ V gamma 9/V delta 2+. The sequence analysis of 16 cDNA clones encoding the V gamma 9-J region revealed that the V gamma 9-Jp combination was strikingly overrepresented but that the junctional (N) region was heterogeneous. This suggested that the gamma delta T cells in PBL from a patient with tularemia were polyclonally expanded.

Targeting of «T» Lymphocytes against Human Hepatoma Cells by a Bispecific Monoclonal Antibody: Role of Different Lymphocyte Subsets

In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4–8+ TCRα/β+ and CD3+4–8-TCRγ/δ+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4+8-TCRα/β+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-α) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.

Use of the V delta 1 variable region in the functional T-cell receptor alpha chain of a WT31+ cytotoxic T lymphocyte clone which specifically recognizes HLA-A2 molecule

We report here the molecular characterization of the T-cell receptor (TCR) expressed by a human HLA-A2 specific cytotoxic T-cell clone named CTL 49. Flow cytometry analysis with a panel of anti-TCR antibodies revealed an OKT3+, WT31+, A13+, BB3-, TCR delta-, delta TCS1-, TCR gamma/delta 1-, OKT4-, and OKT8+ phenotype, suggesting that, in CTL 49, the V delta 1-encoded A13 epitope could be included in its alpha beta TCR. Northern blot analysis confirmed the presence of C alpha, C beta and V delta 1 specific transcripts while no hybridization signal was detected by a C delta specific probe. Polymerase chain reaction (PCR) amplification of the first strand cDNA from CTL 49 with TCR-specific primers and sequence analysis revealed that V delta 1 region is productively rearranged to J alpha and to C alpha regions. This alpha chain pairs with a beta chain composed of V beta 13.2/D beta/J beta 2.3/C beta 2 leading to the expression of a functional TCR complex. These results, in addition to providing further evidence for the sharing of V delta 1 by alpha/beta and gamma/delta TCR, indicate that an alpha/beta T-cell receptor which includes the V delta 1 variable region can be involved in alloreactive recognition.

Increase in TCR gamma delta T lymphocytes in synovia from rheumatoid arthritis patients with active synovitis

To determine the relative presence of TCR gamma delta+ and TCR alpha beta+ T cells in synovial tissue from patients with various types of inflammatory synovitis and in tissues from patients with a number of chronic T cell-mediated conditions, we stained frozen tissue sections with monoclonal antibodies in indirect immunofluorescence assays. In tissues obtained from patients with chronic T cell-mediated granulomatous conditions (Wegener's granulomatosis, lymphomatoid granulomatosis, granuloma annulare, Langerhans' cells granulomatosis, pigmented villonodular synovitis, Takayasu's arteritis, and talc granulomatosis), the T cells present were predominantly TCR alpha beta+, without an increased presence of TCR gamma delta+ cells. In contrast, 6 of 14 (43%) synovia from patients with rheumatoid arthritis (RA) showed increased TCR gamma delta+ T cells (3-10 cells/hpf). The RA synovia with increased TCR gamma delta+ cells present had an increased tissue inflammation score compared to RA synovia with few TCR gamma delta+ cells [18.6 +/- 5.8 versus 11.6 +/- 4.2 (mean +/- SE), P less than 0.05]. In contrast, synovia from patients with osteoarthritis, systemic lupus erythematosus, and trauma did not show an increased presence of TCR gamma delta+ T cells. Thus, in cellular inflammatory infiltrates the presence of increased TCR gamma delta cells is not a component of noninfectious granulomatous inflammation but is found in approximately 40% of RA synovia with high levels of inflammation.

Increase of lymphocytes bearing the gamma/delta T cell receptor in the jejunum of patients with dermatitis herpetiformis

The densities of T cells and of cells bearing the T cell receptors gamma/delta and alpha/delta and the surface antigens CD4 and CD8 in jejunal specimens from 21 patients with dermatitis herpetiformis were compared with those in specimens from 13 untreated adults with coeliac disease and 13 control subjects. In the lamina propria of the jejunum the median density of gamma/delta+ cells was significantly (p less than 0.001) greater in untreated patients with dermatitis herpetiformis than in control subjects (114 v 36 cells/mm2) and similar to that found in the patients with coeliac disease (115 cells/mm2). The difference in gamma/delta+ cell density between patients with dermatitis herpetiformis and control subjects was much greater in the surface epithelium of the jejunum: the median density for 14 untreated patients with dermatitis herpetiformis was 39 cells/mm, for seven patients with dermatitis herpetiformis on a gluten free diet 34 cells/mm, and for control subjects 2 cells/mm; the coeliac patients had the same density as the patients with dermatitis herpetiformis (45 cells/mm). The higher density of cells bearing the alpha/delta T cell receptor in the epithelium (median 77 cells/mm) of untreated patients with dermatitis herpetiformis was associated with a gluten containing diet; in specimens taken from patients with dermatitis herpetiformis on a gluten free diet the median density was similar to that in the control subjects (44 v 39 cells/mm). The increase in the number of lymphocytes bearing the T cell receptor gamma/delta, particularly in the epithelium of the jejunum, seems to be a constant marker for these closely related diseases, whereas the density of alpha/delta+ T cells is dependent on the diet.

CD69-mediated pathway of lymphocyte activation: anti-CD69 monoclonal antibodies trigger the cytolytic activity of different lymphoid effector cells with the exception of cytolytic T lymphocytes expressing T cell receptor alpha/beta

The effect of anti-CD69 monoclonal antibodies (mAbs) on the induction of the cytolytic activity in different types of lymphoid effector cells has been investigated. Three anti-CD69 mAbs, including the reference mAb MLR3 and two new mAbs (c227 and 31C4), have been used. All cloned CD3-CD16+ natural killer (NK) cells belonging to different subsets (as defined by the surface expression of GL183 and/or EB6 antigens) were efficiently triggered by anti-CD69 mAbs and lysed P815 mastocytoma cells in a redirected killing assay. Triggering of the cytolytic activity could also be induced in CD3-CD16- NK clones, which fail to respond to other stimuli (including anti-CD16, anti-CD2 mAbs, or phytohemagglutinin). A similar triggering effect was detected in T cell receptor (TCR) gamma/delta+ clones belonging to different subsets. On the other hand, anti-CD69 mAbs could not induce triggering of the cytolytic activity in TCR alpha/beta+ cytolytic clones. Since all thymocytes are known to express CD69 antigen after cell activation, we analyzed a series of phenotypically different cytolytic thymocyte populations and clones for their responsiveness to anti-CD69 mAb in a redirected killing assay. Again, anti-CD69 mAb triggered TCR gamma/delta+ but not TCR alpha/beta+ thymocytes. Anti-CD69 mAb efficiently triggered the cytolytic activity of "early" thymocytes lines or clones (CD3-4-8-7+), which lack all other known pathways of cell activation. Thus, it appears that CD69 molecules may initiate a pathway of activation of cytolytic functions common to a number of activated effector lymphocytes with the remarkable exception of TCR alpha/beta+ cytolytic cells.

Functionally distinct subsets of human gamma/delta T cells

To determine if effector subsets exist among human gamma/delta T cells, we examined the cytokine production and cytotoxic activity of gamma/delta T cell clones with different accessory molecule phenotypes, V delta and V gamma gene expression, and J gamma rearrangements. T cell clones bearing gamma/delta T cell receptor produce an array of cytokines like alpha/beta T cell clones. Individual gamma/delta T cell clones produced a characteristic array of cytokines without correlation with V delta or V gamma gene expression. However, when phenotypic subsets were considered, CD4+ gamma/delta clones produced significantly higher levels of interleukin 2 and granulocyte-monocyte colony-stimulating factor compared with CD4-CD8- and CD8+ gamma/delta clones. Similarly, when cytotoxic potential was assessed, CD4+ gamma/delta clones exhibited minimal activity when compared with CD4-CD8- and CD8+ adult peripheral blood gamma/delta clones. We conclude that functionally distinct gamma/delta T cell subsets exist and suggest that these subsets may correlate with expression of the CD4 accessory molecule.

Clonally expanded CD3+, CD4-, CD8- cells bearing the alpha/beta or the gamma/delta T-cell receptor in patients with the lymphoproliferative disease of granular lymphocytes

Among 60 retrospectively assessed patients with the lymphoproliferative disease of granular lymphocytes (LDGL), lymphocytes from only 2 patients had the CD3+, CD4-, CD8- phenotype, rarely observed in normal peripheral blood lymphocytes (about 3%). In this paper we report a detailed study of lymphocytes isolated from these two patients. The cells from patients 1 had the CD3+, CD4-, CD8-, WT31-, beta F1-, TCR delta 1+, Ti gamma A-, BB3+, CD7+, CD16-, CD57+ phenotype, while cells from patient 2 had a phenotype even more rarely observed on normal lymphocytes: CD3+, CD4-, CD8-, WT31+, beta F1+, TCR delta 1-, CD7+, CD16-, CD57+. Thus, in only the first case the cells expressed the gamma/delta T-cell receptor (TCR) on the membrane, while the cells from the second case had the alpha/beta TCR. Genetic studies showed that in case 1 the TCR gamma gene was rearranged and the beta chain gene configuration was germline; the TCR mRNA was of normal size for the gamma chain, while that of the beta chain was truncated. Case 2 had the beta and the gamma genes of the TCR rearranged, but only the alpha and beta mRNA were expressed. In agreement with these findings, the delta chain gene of the TCR was rearranged in case 1 and was deleted in case 2. Cytotoxic activity was absent in cells from case 1 and low in case 2; in the latter, the lytic activity could be up-regulated following incubation with IL-2 or an anti-CD3 monoclonal antibody. Our study indicates that CD3+, CD4-, CD8- lymphocytes are rarely expanded in patients with LDGL. The detection of a lymphoproliferative disease of a CD3+, CD4-, CD8-, alpha/beta + cell may contribute to a better characterization of this novel lymphocytic subpopulation.

A novel surface molecule expressed by long-term cultured T and natural killer cells is involved in cell activation

Two monoclonal antibodies (mAb), termed ED6 and LD6, were obtained by immunizing mice with cytotoxic T cell lines expressing the T cell receptor (TcR) gamma/delta. These mAb were selected according to their ability to trigger the cytolytic program of the immunizing cell lines in a redirected killing assay. Both mAb recognized molecule(s) expressed on the surface of most long-term cultured TcR gamma/delta +, TcR alpha/beta + and CD3-CD16+ lymphocytes, while it was absent on resting peripheral blood lymphocytes. In addition both mAb reacted with neoplastic B cell lines, Epstein-Barr virus-transformed B cell lines, small cell lung cancer and glioma cell lines, while no surface reactivity was detected on ovarian, breast, colon and non-small cell lung cancer lines. The functional activity of these mAb was studied by two cytolytic assays. Both mAb were able to trigger the cytolytic program of CD3+TcR gamma/delta + polyclonal cell lines and of a CD3-CD16+ NK cell clone against the murine mastocytoma target cell line P815 (Fc receptor+) in a 4-h 51Cr-release assay. In addition, ED6 and LD6 hybridomas were lysed by TcR gamma/delta + effector cells while other hybridomas (obtained from the same fusion) were not lysed. ED6 and LD6 mAb (in the presence of submitogenic doses of the phorbol 12-myristate 13-acetate) also induced the secretion of interleukin 2 by ED6/LD6+ T cell clones expressing TcR gamma/delta or alpha/beta. mAb-induced surface antigen modulation experiments showed that the antigenic determinant recognized by ED6 and LD6 co-modulated, thus indicating that the two mAb probably recognize the same or closely associated molecules. The molecular characteristics of the antigen recognized by the mAb were investigated by Western blot analysis. The LD6 mAb recognized a major band of approximately 65 kDa, both under nonreducing and reducing conditions. These data indicate that ED6 and LD6 mAb recognize a novel non-lineage-specific activation antigen which is involved in the induction of the functional program of long-term cultured T or natural killer cells.

Involvement of the interleukin 4 pathway in the generation of functional gamma delta T cells from human pro-T cells

We have used the technique of in situ hybridization to investigate the transcription of genes encoding the CD3 complex and the lymphokine interleukin 4 (IL-4) by human pro-T cells--i.e., cells that phenotypically resemble those T-cell precursors that colonize the thymus during early intrathymic development. CD1-2-3-4-7+8-45+ pro-T cells isolated from postnatal thymi via immunoselection with a panel of specific monoclonal antibodies are already committed to the T-cell lineage because most of them transcribe the genes encoding the delta and epsilon chains of the CD3 complex. About half of such pro-T cells synthesize IL-4 mRNA in the absence of any exogenous stimulation. Upon culture with IL-4, pro-T cells extensively proliferate and differentiate into functionally competent, mature gamma delta T cells expressing a T-cell receptor repertoire similar to that of gamma delta T cells that can be found in postnatal thymus. The IL-4 response of pro-T cells is not mediated by induction of the interleukin 2 (IL-2)-IL-2 receptor pathway and, unlike IL-2-driven T-cell differentiation, does not require the presence of stromal cells. Taken altogether, these findings suggest that an autocrine IL-4-mediated pathway might be implicated in early thymocyte differentiation--namely, in the generation of T cells bearing the gamma delta T-cell receptor.

Selective expansion of T cells bearing the gamma/delta receptor and expressing an unusual repertoire in the synovial membrane of patients with rheumatoid arthritis

In a study of 7 patients with rheumatoid arthritis (RA), we characterized the T cell population present in the synovial membrane, thought to be the location where T cells trigger the disease. Synovial membrane lymphocytes from the RA patients were found to have a selective expansion of gamma/delta T cells (8.8% in synovial membrane versus 4% in peripheral blood). Expansion of the gamma/delta T cell subset was not found in the synovial membrane of patients with osteoarthritis. We characterized the gamma/delta T cell repertoire using monoclonal antibodies Ti gamma A, BB3, and delta TCS1, which recognize the gene products encoded by V gamma 9, V delta 2, and V delta 1-J delta 1, respectively. The majority of the synovial gamma/delta T cells did not express the repertoire encoded by these genes, which is found in nearly 100% of the peripheral blood gamma/delta T cells of healthy volunteer donors and in the thymus at early stages of development. We conclude that the synovial membrane of patients with RA displays a selective expansion of a specific population of gamma/delta T cells expressing a clonotypic receptor not yet serologically defined, which might be implicated in the development of the disease.

Predominant appearance of gamma/delta T lymphocytes in the liver of mice after birth

gamma/delta T lymphocytes residing in the liver of mice were systematically characterized with respect to their age-related variation, phenotype and V gene segment usage of gamma/delta T cell receptor (TcR). Previous human and murine studies have shown that a high proportion of gamma/delta T cells reside in the liver and that such liver gamma/delta T cells have lymphoblastic morphology and can spontaneously proliferate in vitro. In the present study, a predominant appearance of gamma/delta T cells (up to 23% among CD3+ cells) in the liver was confirmed in 4-week old mice of various strains. gamma/delta T cells in the liver preferentially co-expressed CD8 antigens, whereas the vast majority of gamma/delta T cells in the spleen lacked the CD8 antigens. The identification of gamma/delta T cells in various lymphoid and non-lymphoid organs also revealed the liver to be one of the organs where gamma/delta T cell are most abundant. The level of such liver gamma/delta T cells showed a clear age-related variation. In the fetal stage and just after birth, gamma/delta T cells were not detectable in the liver (less than 0.2%). However, a significantly higher percentage of gamma/delta T cells among both the total population of mononuclear cells and CD3+ cells was detected in the liver of young 2- to 8-week-old mice; this percentage subsequently declined. As the total number of liver mononuclear cells increased in aged mice, the absolute number of liver gamma/delta T cells also increased as a function of age. V gene segment usage analysis by the polymerase chain reaction method demonstrated that V gamma 1 or V gamma 2/V delta 6 were preferentially used by liver gamma/delta T cells. The age-related increase of gamma/delta T cells was more prominent in the liver of athymic nude mice, and such gamma/delta T cells highly co-expressed the CD8 antigens and also utilized the V gamma 1 or V gamma 2/V delta 6 for gamma/delta Tcr. The predominant appearance of unique gamma/delta T cells in the liver, which was inversely related to the existence of the thymus, indicates that these gamma/delta T cells may differentiate extrathymically in the liver.

Bispecific monoclonal antibodies directed to CD16 and to a tumor-associated antigen induce target-cell lysis by resting NK cells and by a subset of NK clones

CD16 surface antigens represent activatory molecules in CD3-16+ NK cells. In order to target NK cells against relatively NK-resistant ovarian carcinomas, we used an anti-CD16 monoclonal antibody (MAb) (VD4), together with an anti-ovarian carcinoma-associated antigen (MOV19), to construct biMAbs. To this end, hybrid hybridomas were generated by fusing a TK-deficient VD4 hybridoma mutant with a HGPRT-deficient MOV19 hybrid. Supernatants from hybrid hybridomas that had been selected in HAT medium were screened for their ability to induce a CD3-16+ NK clone to lyse an MOV19+ ovarian carcinoma cell line in a 4-hr 51Cr-release assay. The NMB.45 hybrid hybridoma secreted a biMAb which triggered lysis of MOV19+ but not of MOV19- target cells. Some degree of target cell lysis was also observed with MOV19 MAb (due to ADCC mechanisms), while the VD4 MAb was ineffective. HPLC fractionation of MAbs secreted by the hybrid hybridoma made it possible to identify 4 different peaks, one of which appeared to contain functional biMAb molecules. HPLC-purified biMAb (100 ng/ml) induced resting PBL to lyse the "NK-resistant" IGROVI ovarian carcinoma cell line. Fresh MOV19+ tumor cells were also lysed, although with lower efficiency. When IL-2-activated lymphocytes were used as a source of effectors, biMAb caused only minor increases in the IL-2-induced cytolytic activity. Further analyses of the effect of biMAb were performed at the clonal level. Among CD3-16+ NK cell clones, a clear enhancing effect could be observed only in GL183+ but not in GL183- clones. In CD3+ cytotoxic clones a triggering effect could be detected in one out of 4 TCR gamma/delta+ clones but not in TCR alpha/beta+ clones.

Molecular and cellular analysis of human T lymphocytes expressing gamma delta T-cell receptor

A minor subset of T lymphocytes expresses a CD3-associated TCR composed of gamma and delta chains. The majority of TCR gamma/delta+ cells lack surface CD4 and CD8 antigen and do not react with WT31 mAb. These negative criteria were utilized in early studies to identify TCR gamma/delta+ cells. More recently, mAb to TCR gamma/delta, selected in different laboratories, have permitted the direct identification of TCR gamma/delta+ cells and their subsets. TCR gamma/delta molecules were found to be heterogeneous in size and charge mobility. Two major forms of TCR gamma/delta could be identified that are characterized by the presence or absence of an inter-chain disulphide bond. Biochemical analysis originally suggested that a precise correlation existed between reactivity with BB3 or delta TCS1/A13 mAb and expression of a disulphide (C gamma 1-encoded) or non-disulphide linked (C gamma 2-encoded) form of TCR gamma/delta. However, more recent studies have indicated that these mAb react with the molecular product of V delta 2 or V delta 1, respectively, mAb directed to one or another form of TCR gamma/delta activate the functional program of the cell, leading to intracellular Ca++ mobilization, lymphokine production and triggering of the lytic machinery. Analysis of the target molecules for TCR gamma/delta-mediated recognition revealed that at least some TCR gamma/delta+ cells are capable of specific responses to (allo)antigen and that polymorphic determinants of class I molecules can be recognized (as shown by the specific lysis of P815 cells transfected with HLA-24 allele). Unlike TCR alpha/beta+ cells, TCR gamma/delta+ cells are homogeneously composed of cytolytic precursors, as shown by the analysis of a large panel of clones in both lectin-dependent and redirected killing assays. In spite of their LGL morphology, freshly isolated TCR gamma/delta+ cells do not lyse NK-sensitive targets but do so after exposure to rIL-2. A modest cytolytic activity, however, could be induced also in fresh cells by anti-TCR/CD3 mAb in a redirected killing assay. Analysis of the distribution of the subsets expressing different TCR gamma/delta types showed that BB3+ cells are prevalent in the peripheral blood and virtually absent in the thymus; in contrast, A13+ (delta TCS1+) cells represent the majority of TCR gamma/delta+ thymocytes. Electron microscopic analysis of fresh TCR gamma/delta+ cells showed an extended cytoplasm containing numerous electron-dense granules identifiable as primary lysosomes. Upon stimulation with IL-2, TCR gamma/delta+ cells, similar to other LAK cells, display an increase in their cytoplasmic granules together with a redistribution of cytoskeletal structures.(ABSTRACT TRUNCATED AT 400 WORDS)

Generation and function of gamma delta T cells after allogeneic bone marrow transplantation in humans: comparison in absence or presence of HLA-matched or mismatched thymus

We have observed two patients who exhibited an exclusive increase of delta TCS1+ subset of gamma delta T cells in the peripheral blood after bone marrow transplantation (BMT). In one case with severe combined immunodeficiency (SCID) who received haploidentical BMT from his father, gamma delta T cells appeared only after thymus transplantation. However, his T cell-mediated immunity remained severely defective despite the generation of T cells of donor origin. In the other case with aplastic anemia, delta TCS1- gamma delta T cells began to increase in the peripheral blood later. This indicates that the thymus is necessary for the generation of gamma delta T cells and that the delta TCS1+ subset is dominant in the early stages of their ontogeny. delta TCS1+ T cell lines were established from both patients, and allo-reactivity was investigated. The cell line from the latter case reacted to recipient cells in a mixed lymphocyte reaction, but did not show cytotoxity to the allogeneic cells including recipient cells. The other cell line, from the former case, did not react to either donor or recipient cells. This indicates that an intact thymus is needed for gamma delta T cells to acquire allo-reactivity. Both cell lines showed MHC non-restricted cytotoxity against NK-sensitive target cells.

Polymyositis mediated by T lymphocytes that express the gamma/delta receptor

BACKGROUND

The invasion and destruction of nonnecrotic muscle fibers by CD8+ cytotoxic T cells is considered a hallmark of polymyositis. In the cases of polymyositis reported so far, the autoinvasive CD8+ T cells expressed the common form of T-cell receptor for the recognition of antigen, the so-called alpha/beta T-cell receptor. We describe a 69-year-old man with polymyositis mediated by CD4-, CD8- T cells expressing the recently discovered, uncommon gamma/delta T-cell receptor.

METHODS

We used immunofluorescence or immunoperoxidase techniques to study frozen sections of muscle from our patient, who had mild weakness of cervical and proximal limb muscles, and from control patients with polymyositis, inclusion-body myositis, dermatomyositis, or granulomatous myopathy with monoclonal antibodies against T-cell-related antigens (CD2, CD3, CD4, CD8, and gamma/delta T-cell receptor), B cells (CD22), major histocompatibility complex (MHC) and MHC-related antigens (MHC Class I, CD1a, CD1b, and CD1c), and the 65-kd heat-shock protein. The membrane contacts between the autoinvasive cells and the sarcolemma were investigated by electron microscopy.

RESULTS

In the patient described here, but not in 28 others with inflammatory myopathies, myriad gamma/delta T cells surrounded and invaded nonnecrotic muscle fibers. All muscle fibers were highly reactive for MHC Class I antigen and the 65-kd heat-shock protein. Treatment with prednisone improved the clinical and histologic findings.

CONCLUSIONS

Polymyositis can be mediated by gamma/delta T cells. This new form of polymyositis appears to be highly responsive to steroids.

Activated CD3- CD16+ natural killer cells express a subset of the lymphokine genes induced in activated alpha beta + and gamma delta + T cells

In this study we analysed the potential of highly purified polyclonal TcR alpha beta+, TcR gamma delta + and CD3- NK cells, to produce lymphokines in response to mitogenic stimulation. RNA hybridizations were performed to detect with high sensitivity the induction of multiple lymphokine genes. Upon stimulation with lectin and phorbol ester TcR gamma delta + lymphocytes expressed the same set of lymphokine genes as the TcR alpha beta + lymphocytes expressed the same set of lymphokine genes as the TcR alpha beta + lymphocytes, which included IL-2, -3, -4, -5, GM-CSF, TNF alpha and beta, IFN gamma. In contrast, a more limited set of lymphokine genes (GM-CSF, TNF alpha and beta, IFN gamma) was induced in activated CD3- NK cells, thus indicating that this subpopulation of cells may display different regulatory functions, with respect to CD3+ T lymphocytes.