Characterization of CD3+, CD4-, CD8- clones expressing the putative T cell receptor gamma gene product. Analysis of the activation pathways leading to interleukin 2 production and triggering of the lytic machinery

Graves' disease: phenotypic and functional analysis at the clonal level of the T-cell repertoire in peripheral blood and in thyroid

We have investigated at the clonal level the repertoire of intrathyroid and peripheral T lymphocytes in three patients with Graves' disease using a high efficiency cloning technique. Clonal efficiencies ranged from 10 to 31% for intrathyroid, and from 19 to 100% for peripheral T cells. In Graves' disease the phenotypic analysis showed similar percentages of CD3+ CD4+ CD8- and CD3+ CD4- CD8+ clones in thyroid infiltrates and peripheral blood. The functional evaluation showed similar or lower proportions of cytolytic clones in thyroid infiltrates with respect to peripheral blood. Furthermore, the proportions of intrathyroid and peripheral T-cell clones capable of releasing interleukin-2 and/or gamma-interferon in response to mitogen stimulation were similar. Finally, 44% of intrathyroid clones were neither cytolytic nor able to release IL-2 and gamma-interferon. These results are strikingly different from those obtained in Hashimoto's thyroiditis, where the large majority of intrathyroid T-cell clones are cytolytic and the proportions of clones able to release gamma-IFN are remarkably increased in thyroid infiltrates when compared to those obtained from peripheral blood. Taken together, these data suggest a different role for T lymphocytes in the pathogenesis of the two major human autoimmune thyroid diseases.

Expression of the T cell gamma gene by a functionally defined human T cell clone. Characterization at DNA, RNA, and cell membrane level

In the present study we describe one CD2+CD3+ clone termed DS6 which expressed neither CD4 nor CD8 differentiation antigens and failed to react with WT31, a monoclonal antibody directed against the T cell antigen receptor alpha/beta heterodimer. This clone was isolated from peripheral blood T lymphocytes of a patient with a prolonged immunodeficiency after allogeneic bone marrow transplantation. Normal-sized T cell gamma gene transcripts were detected in DS6 by northern analysis, whereas no mature beta or alpha chain mRNA were found. The rearrangement of TCR beta chain genes and T cell gamma genes was analysed. While in DS6, TCR beta chain genes remain in germinal configuration, and a unique pattern of monoallelic T cell gamma gene rearrangement was observed. The rearrangement involves the recently described V gamma 5 segment and the J gamma 1 joining segment, which is located upstream of the C gamma 1 constant region. To determine the molecular structure present on DS6, an immunoprecipitation was performed with monoclonal anti-CD3 antibody and a rabbit antiserum raised against gamma protein. We have observed, in association with the CD3 complex, a 90 kDa structure which under reducing conditions resolves into three subunits of 45, 40 and 37 kDa. We demonstrated that the rabbit anti-gamma serum only immunoprecipitates the two lower bands. The upper band corresponds to a presently undefined T cell receptor chain. Next, we showed the non major histocompatibility complex (MHC)-restricted cytolytic activity exhibited by these CD3+CD4-CD8- cloned T cells and inhibition of the natural killer (NK)-like activity by the anti-CD3 monoclonal antibody. The triggering of CD2 or CD3 molecules increased IL-2 receptor expression on DS6 but failed to induce cell proliferation. This contrasts with recent results obtained with gamma-expressing T cell clones and illustrates the functional heterogeneity of the cells bearing the second T cell receptor.

Antigen recognition by human T cell receptor gamma-positive lymphocytes. Specific lysis of allogeneic cells after activation in mixed lymphocyte culture

These experiments were designed to define the ability of human TCR-gamma+ cells to recognize allogeneic cells. TCR-gamma+-enriched populations were obtained by treating peripheral blood E-rosetting cells with anti-CD4 and anti-CD8 mAbs. The resulting populations were CD2+4-8- expressed variable proportions of CD3+ cells (40-90%), and did not react with the WT31 mAb, which is specific for a framework determinant of the alpha/beta heterodimer that serves as receptor for antigen on most human T lymphocytes. After mixed lymphocyte culture with irradiated allogeneic cells for 7 d and 3 additional days in rIL-2 (100 U/ml), cells underwent proliferation in three of five individuals tested. In addition, MLC-derived cells lysed 51Cr-labeled PHA-induced blasts derived from the allogeneic cells used as stimulator, but not allogeneic unrelated or autologous blast cells. No cytotoxicity against autologous or allogeneic target cells could be induced by culturing CD3+4-8-WT31- lymphocytes in MLC with irradiated autologous cells. Surface iodination of allogeneic MLC-activated CD3+4-8-WT31- cells followed by lysis in 1% digitonin and immunoprecipitation with anti-CD3 mAb indicated that the CD3-associated molecules consisted of a major 45-kD band and a minor band of 43 kD. Northern blot analysis showed that mRNA for the gamma chain was expressed at high levels, whereas mRNAs for alpha and beta chains were missing. These data support the notion that TCR-gamma rather than TCR-alpha/beta is expressed in allospecific CD3-4-8-WT31- cell populations. Clones were further derived from MLC-stimulated CD3+4-8-WT31- populations. All the seven clones studied in detail maintained the surface phenotype as well as the cytolytic pattern of the original MLC populations, thus only specific allogeneic PHA-induced blasts were lysed. NK-sensitive as well as NK-resistant tumor targets were variably susceptible to lysis; therefore, specific cytolytic activity against allogeneic cells was not necessarily linked to the expression of MHC-nonrestricted cytotoxicity against tumor cells.

Stimulation and proliferation of CD4+ peripheral blood T lymphocytes induced by an anti-CD4 monoclonal antibody

There is experimental evidence that the CD4 molecule participates in the antigen-driven activation of T cells expressing this surface glycoprotein. Whether CD4, a member of the immunoglobulin supergene family, acts as a ligand-binding molecule and/or is directly involved in the activation pathway has yet to be established. In this study, we show that human CD4+ lymphocytes can be activated by exposure to the anti-CD4 monoclonal antibody (mAb) B66. Normal peripheral blood CD4+ cells were induced to proliferate and to synthesize interleukin 2 (IL 2) by the antibody. The specificity of the antibody stimulatory activity was tested by using IL 2-producing clones bearing either CD4 or CD8 on their surface. IL 2 production was induced by mAb B66 in CD4+, but not CD8+, clones, whereas both types of clones responded to stimulation by the anti-CD3 mAb Leu-4. Despite its unique stimulatory activity, mAb B66 shared with other anti-CD4 antibodies the ability to inhibit the specific cytolytic activity of CD4+ effector cells. These results clearly indicate that cross-linking of surface CD4 molecules with appropriate antibodies can fully activate CD4+ lymphocytes. Whether the natural ligand for CD4 can trigger this activation pathway remains to be defined.

CD3+4-8-WT31-(T cell receptor gamma+) cells and other unusual phenotypes are frequently detected among spontaneously interleukin 2-responsive T lymphocytes present in the joint fluid in juvenile rheumatoid arthritis. A clonal analysis

T lymphocytes (E rosetting cells) isolated from the joint fluid of four patients with juvenile rheumatoid arthritis (JRA) were first analyzed for surface antigen expression. Approximately 15% of cells were CD25+ (interleukin, IL, 2 receptor positive), in addition, a remarkable proportion of cells expressed the CD2+3- phenotype. CD3+ cells outnumbered the sum of CD4+ and CD8+ cells as well as the cells reactive with the WT31 monoclonal antibody (which recognizes a framework determinant of the alpha/beta T cell receptor). Purified T cells were cloned under culture conditions (1% phytohemagglutinin, PHA plus IL2) which allow clonal expansion of most peripheral blood T lymphocytes. Under these conditions proliferating cells ranged from 25 to 65%; clones (derived from microcultures containing 0.5 or 0.25 cells/well) were tested for cytolytic activity against P815 cells (in the presence of PHA) or against the natural killer (NK)-sensitive K562 target cells. Fifty-four percent and 73% of clones obtained from the two patients with the polyarticular form of the disease displayed cytolytic activity in the lectin-dependent assay. Cytolytic clones were 22 and 29% in the two patients with single joint involvement. About half of all cytolytic clones displayed NK-like activity. Surface antigen analysis revealed that, in addition to conventional CD3+4+8- and CD3+4-8+, a noticeable fraction of clones (50/202) displayed unusual surface phenotypes. In particular, 33/50 coexpressed CD4 and CD8 antigens; 7/50 were CD2+3-4-8- and displayed NK-like activity; 10/50 expressed CD3 but lacked both CD4 and CD8 antigen and did not react with the WT31 monoclonal antibody. In order to allow selective growth of IL2-responsive cells, T lymphocytes were also cloned directly in IL2. As much as 57% of all clones thus obtained (48/84) displayed cytolytic activity. Moreover, about half expressed unusual surface phenotypes including CD2+3-4-8-, CD3+4+8+ and CD3+4-8-WT31-. Given the accumulation at the site of the joint involvement of unusual T cells, most of which displayed cytolytic activity and were likely to represent cells activated in vivo (IL2 responsive), one may speculate that these cells may be involved in the injury process.