Jos Even

T-cell repertoire diversity and clonal expansions in normal and clinical samples

Improved polymerase chain reaction (PCR)-based methods now permit a more in-depth analysis of the repertoire of T cells recovered in biological samples from mice and humans. At a certain level of resolution, the diversity of the T-cell repertoire can be readily estimated and clonal expansions become easily detectable. As discussed here by Christophe Pannetier, Jos Even and Philippe Kourilsky, these improvements allow a better appreciation of the degree of reproducibility of immune responses, both in mice and humans, and should have a significant impact on clinical investigations.

T-cell repertoires in healthy and diseased human tissues analysed by T-cell receptor β-chain CDR3 size determination: evidence for oligoclonal expansions in tumours and inflammatory diseases

Many examples of oligoclonal T-cell expansion in infiltrated diseased tissues have been reported. However, it remains to be established whether such observations can be generalized and to what extent oligoclonal patterns obtained after in vitro culture of T-cell infiltrates reflect in vivo situations. Using new high resolution analysis which requires no in vitro cellular expansion, we detected such oligoclonal T-cell expansions in 7/7 melanoma tumour biopsies, 3/3 biopsies of inflammatory skin during acute graft versus host disease (aGVHD) after allogeneic bone marrow transplantation (alloBMT) and 7/7 synovial membranes from patients with rheumatoid arthritis. Thus, oligoclonal T-cell expansions are readily observed when a sufficiently sensitive detection method is used, suggesting that similar expansions are the rule among T-cell infiltrates in different diseases. This observation and the monitoring of the in vivo evolution of such expansion during the course of the disease and during in vitro culture should have important clinical implications.

Involvement of Soluble CD95 in Churg-Strauss Syndrome

Deficiency of CD95 (Apo-1/Fas)-mediated apoptosis has recently been found in some autoimmune lymphoproliferative disorders due to inherited mutations of the CD95 gene. In this study, impairment of CD95 ligand-mediated killing of lymphocytes and eosinophils in Churg-Strauss Syndrome (CSS), which was a result of variation of CD95 receptor isoform expression, is demonstrated. Compared to those from healthy individuals, peripheral blood lymphocytes from eight CSS patients exhibit a switch from the membrane-bound CD95 receptor expression to its soluble splice variant, which protects from CD95L-mediated apoptosis. In five out of seven CSS patients recurrent oligoclonal T cell expansions were found, all using a Vbeta-gene from the Vbeta21 family associated with similar CDR3 motifs, indicating the predominance of T cell clones of a similar specificity in the CSS patients. In two of them, the effect of immunosuppressive therapy was studied. In both cases aberrant overexpression of the soluble CD95 receptor isoform and deviations from normal TCR Vbeta-gene usage normalized in parallel with the clinical improvement. Furthermore, soluble CD95 was identified as a survival factor for eosinophils rescuing eosinophils from apoptosis in the absence of growth factors in vitro. Given the role of eosinophils as effector cells in CSS, these findings suggest that soluble CD95 may be mechanistically involved in the disease.

Severe and long-lasting disruption of T-cell receptor diversity in human myeloma after high-dose chemotherapy and autologous peripheral blood progenitor cell infusion.

Vaccine‐based strategies are currently under investigation as a means of inducing tumour‐specific immune responses and improving the clinical outcome of multiple myeloma (MM) patients in remission after high‐dose chemotherapy and peripheral blood progenitor cell (PBPC) infusion. The immune competence of these patients was investigated by determining the overall diversity of the T‐cell receptor (TCR) repertoire in the peripheral blood (PB) and bone marrow (BM). The average time after transplantation was 13 months. The clonality and reciprocal usage of BV gene segments (TCRBV repertoire) was estimated at the cDNA level and membrane protein expression. The TCRBV repertoire of MM was severely disrupted compared with age‐matched normal donors. On average, one‐third of the total repertoire in both the PB and the BM consisted of T cells expressing oligoclonal TCRβ transcripts. Flow cytometry showed an increased frequency of abnormally expanded BV subfamilies at both sites. BV expansions were predominantly CD8+ and had the phenotype of antigen‐experienced memory T cells as well as T cells with the naive phenotype. Oligoclonality was not restricted to phenotypically expanded BV subfamilies, but also involved normally represented BV subfamilies. The TCR repertoire of MM in remission was then compared with monoclonal gammopathy of undetermined significance (MGUS) and MM patients at diagnosis. The degree of TCR diversity was similar in age‐matched normal donors and MGUS, but progressively decreased from MGUS to MM at diagnosis and then to MM in remission. These data indicate that: (1) there is a long‐lasting and severe disruption of TCR diversity after high‐dose chemotherapy and PBPC infusion, and (2) the extent of TCR disruption may affect the clinical outcome of vaccine‐based strategies delivered at the stage of minimal residual disease.

CD95 ligand expression as a mechanism of immune escape in breast cancer

Interaction of CD95 (Apo‐1/Fas) and its ligand (CD95L) plays an important role in the regulation of the immune response, since CD95+ lymphocytes may be killed after engagement of the CD95 receptor. Studying the CD95/CD95L system in 40 cases of breast cancer, the malignant cells expressed CD95L, but lost CD95 expression, when compared with non‐malignant mammary tissue. Jurkat T cells incubated on breast cancer sections underwent CD95L‐specific apoptosis. The rate of apoptosis correlated with the CD95L mRNA levels of the tissue samples. In four breast cancer cell lines, CD95L expression was increased by interferon‐γ (IFN‐γ), which resulted in higher levels of CD95L‐specific apoptosis in co‐cultured Jurkat T cells. Since IFN‐γ is mainly secreted by activated T cells, up‐regulation of CD95L in breast cancer cells in response to IFN‐γ may thus counterselect activated tumour‐infiltrating T cells and favour the immune escape of breast cancer. As demonstrated by inhibition of matrix metalloproteinases, CD95L expressed on breast cancer cells can also be shed from the cell membrane into the culture supernatant. Supernatants derived from cultured breast cancer cells induced apoptosis in Jurkat T cells via CD95L. In breast cancer patients, depletion of CD4+ and CD8+ peripheral blood lymphocytes was significantly correlated with CD95L expression in the tumours. This might be suggestive for a relationship between CD95L expression by breast cancer and systemic immunosuppression.

Acute graft versus host disease due to T lymphocytes recognizing a single HLA-DPB1*0501 mismatch.

Analysis of a large number of unrelated bone marrow transplantations (BMT) has shown that HLA-DP incompatibility did not detectably influence the risk for acute graft-versus-host disease (aGVHD). Accordingly, it was proposed that HLA-DP determinants did not function as transplantation antigens in the same way as HLA-A, -B, or -DR. We have previously shown that HLA-DP (as well as HLA-A, -B, -DQ, or -DR)-specific T cells could be isolated from skin biopsies of patients who developed an aGVHD after semiallogeneic BMT. Nevertheless, whether a single HLA-DP mismatched allele could induce a detectable allo-specific reaction in vivo after BMT remained to be established. To directly address this issue we studied one patient who presented aGVHD after receiving purified CD34+ bone marrow (BM) cells from an unrelated donor with a single HLA-DP mismatch in the GVHD direction. To characterize the immunological events associated with GVHD, we analyzed the peripheral T cell repertoire, the T cell receptor Vbeta diversity, and the specificity of T cells invading a skin biopsy at the onset of GVHD. Our results demonstrated that a large fraction of skin-infiltrating lymphocytes, which expressed diverse T cell receptors, were reactive against this single HLA-DPB1 *0501 mismatch and consequently that a single HLA-DP mismatch between BM donor and recipient can activate a strong T cell response in vivo.

Regulation of CD95 (APO‐1/ FAS) ligand and receptor expression in squamous‐cell carcinoma by interferon‐γ and cisplatin

CD95 (Apo‐1/Fas) ligand (CD95L) expression has been observed in various malignancies. In human primary cell lines from a squamous cell carcinoma (SCC) of the vulva, the effect of cisplatin (CDDP) and IFNγ on the expression of CD95L and its 2 receptor isoforms, CD95 transmembrane (CD95tm) and CD95 soluble receptor, was studied at the mRNA and protein levels. Addition of CDDP and IFNγ increased CD95L mRNA levels in the primary cell line 6‐fold and 1.7‐fold, respectively. In comparison, CD95tm mRNA levels were diminished by CDDP but increased 8‐fold upon IFNγ challenge. CD95L expressed by SCC cells was functionally relevant since these cells were able to induce CD95‐specific apoptosis in autologous lymphocytes from the SCC‐bearing patient. Thus, CD95L expression in SCC may contribute to tumor‐associated immunosuppression, which may be modulated by CDDP and IFNγ. In tumor samples of the primary SCC, CD95L expression was enhanced in the area of the border between invasive tumor tissue and surrounding stroma cells. The locally restricted over‐expression of CD95L was congruent with the arrangement of apoptotic stroma cells in the direct vicinity of invading tumor tongues, suggesting a role as invasion factor for CD95L. Int. J. Cancer 80:564–572, 1999.

Restriction of the T‐cell repertoire in tumor‐infiltrating lymphocytes from nine patients with renal‐cell carcinoma relevance of the CDR3 length analysis for the identification of in situ clonal T‐cell expansions

Renal‐cell carcinoma (RCC) is one of the human cancers which respond best to immunotherapy. To better characterize the mechanism of the immune response in RCC, we analyzed the T‐cell receptor (TCR) β‐chain repertoire in primary RCC, metastases and paired peripheral blood lymphocytes (PBL) from 9 patients. For 3 of these, we also analyzed T cells recovered from normal kidney, or from tumor‐involved lymph nodes as well as tumor‐infiltrating lymphocytes (TIL) expanded in vitro for adoptive immunotherapy. The initial semi‐quantitative RT‐PCR method for definition of the Vβ gene usage was not informative enough to distinguish intratumoral clonal T‐cell expansions. In contrast, the length pattern analysis of the complementary determining regions 3 (CDR3) allowed oligoclonal T‐cell populations to be detected in fresh TIL from the 9 patients with RCC. Furthermore, these oligoclonal TIL populations were not present in normal renal tissue, autologous PBL or tumor‐involved lymph nodes. Different clonal T‐cell expansions were identified in the primary tumor and in a pulmonary metastasis from the same patient. The detection of clonal T‐cell populations observed in RCC suggests an in situ expansion in response to potential tumor antigens. This report provides an overall and accurate description of the T‐cell repertoire in a significant number of samples from patients with RCC.

T-cell repertoire analysis in chronic plaque psoriasis suggests an antigen-specific immune response

Psoriasis is a chronic inflammatory cutaneous disease of unknown etiology. Activation of T cells is thought to play a major role in the pathophysiology of psoriasis. In order to gain insight into the nature of the antigen (superantigen or nominal protein antigen) involved in psoriatic lesions, we have used a RT-PCR method to analyze the frequency of the 24 T cell receptor V beta chain (TCRBV) subfamilies and the size of the antigen-binding region (CDR3), using the immunoscope assay, in skin lesions of patients with chronic plaque-type psoriasis. Semi-quantitative analysis showed that no significant difference in V beta subfamily usage could be detected in T lymphocytes infiltrating lesional skin as compared to blood lymphocytes. Alternatively, determination of the size distribution of the CDR3 of all the V beta subfamilies revealed only in psoriatic skin a marked TCR oligoclonality defined by the presence in 3 to 5 V beta subfamilies of a single predominant CDR3 size which was associated with a unique V beta-J beta combination. Identical patterns of CDR3 length and V beta-J beta combination profiles were found in symetrical lesional sites from two psoriatic patients. This type of skewed CDR3 size profile is reminiscent of a local stimulation of T lymphocytes by nominal protein antigens. These data suggest that T lymphocytes infiltrating plaque-type psoriatic skin comprise expansions of oligoclonal T cells in response to stimulation by an antigen present in the skin.

SPREAD OF CLONAL T-CELL EXPANSIONS IN RHEUMATOID ARTHRITIS PATIENTS

Despite a large number of studies identifying expanded T-cell clones among infiltrating lymphocytes, little is known about their distribution in patients suffering from rheumatoid arthritis. To evaluate the clonality of alpha/beta T-cell populations in arthritic locations and PBL, we determined the CDR3 size lengths of TCR beta-chain transcripts using BV (Vbeta), BC (Cbeta), BJ (Jbeta), and clonotype-specific primers. Transcripts from PBL of healthy donors show gaussian profiles of approximately eight CDR3 size peaks in most BV subfamilies. Dominant peaks standing out above the normal background identify expansions of one or several T-cell clones within a given BV subfamily. The analysis of six patients suffering from rheumatoid arthritis showed clonal expansions in all samples including PBL. Synovial tissue infiltrates revealed less complex repertoires with a greater number of expanded clones than PBL. Expanded clones varied from one patient to another; no recurrences were observed. Most interestingly, identical clones were identified bilaterally in arthritic knee joints and PBL from the same patient. Our data show that given T-cell clones are not only locally expanded but can also be found in the periphery, and strongly suggest that many similar clones spread throughout the bodies of patients.