In vitro culture of heart biopsy specimens from patients after transplantation in media containing recombinant human interleukin-2 led to the exudation of host mononuclear-cell infiltrates. Cloned T-cell lines were prepared from such infiltrates and studied for donor-specific mixed lymphocyte reaction and cytotoxic T-lymphocyte activity. Although most T-cell clones (greater than 50%) showed donor-specific reactivity, a small but distinct frequency (2% to 10%) of the cloned T-cell lines did not proliferate against donor or third-party stimulator cells. Of interest was our finding that addition of these non-donor-reactive cloned T-cell lines to autologous peripheral blood mononuclear cells markedly suppressed their donor-specific, but not third-party major histocompatibility complex, unrelated proliferative response and prevented the generation of donor, but not third-party, major histocompatibility complex unrelated cytotoxic T-lymphocyte function. The suppression was not secondary to lysis of donor stimulator cells, lysis of autologous donor-specific CD4+ lymphoblasts, or by selective consumption of interleukin-2. The suppression was mediated at the initiation of sensitization (precursor cell level). These suppressor cells expressed CD3, CD8, CD45RO, and the alpha, beta T-cell receptor, but not CD4 or CD56. These cloned T-cell lines will provide unique reagents to study the molecular basis by which these cells exert their regulatory function.

Antigens, CD↗

PubMedDate not supplied

Characterization of human heart-infiltrating cells after transplantation. VI. Differences in the cytokines produced by individual CD4+ cloned T-cell lines with apparently identical antiidiotype-like reactivity.

Studies of cultures and cloned T-cell lines from mononuclear cell infiltrates in cardiac biopsy specimens have provided a unique resource to study the cellular basis of human organ allograft rejection. Our laboratory has previously shown that biopsy specimens placed on autologous donor MHC-class-II-specific cloned T-cell lines from previous cardiac biopsies led to the isolation of cloned T-cell lines, which appeared to be functionally "antiidiotypic" in nature. Detailed functional analysis of such CD4+ individual antiidiotype-reactive cloned T-cell lines revealed that although some augmented the proliferative response of autologous idiotype-bearing cloned T-cell lines against donor stimulator cells, others markedly suppressed the proliferative response; thus, although each of these antiidiotype-like reactive cloned T-cell lines appears to specifically react with the same idiotype-bearing donor MHC-class-II-specific cloned T-cell line, they were functionally heterogeneous. Analysis of cytokines secreted by these individual clones showed that the antiidiotype-reactive cloned T-cell lines that suppressed the response of idiotype-bearing cells appear to secrete predominantly interferon gamma, whereas those antiidiotype-reactive cloned T-cell lines that augmented the response do not secrete interferon gamma but secrete interleukin-2, -4, and -6. These preliminary data suggest that differences in the predominant cytokines secreted by these individual antiidiotype-reactive cloned T-cell lines may account for their functional differences.

Antibodies, Anti-Idiotypic↗

PubMedDate not supplied

Indirect presentation of donor histocompatibility antigens contributes to the allogeneic response against human cardiac myocytes.

Normal human cardiac myocytes failed to induce proliferative responses of peripheral blood mononuclear cells from major histocompatibility complex (MHC)-disparate individuals. Induction of cell-surface MHC antigens on such myocytes before culture still failed to induce alloproliferative responses. Similar data were obtained with cocultures of a human cardiac myocyte (W1) cell line and allogeneic lymphocytes. Addition of interleukin (IL)-1, IL-2, or IL-1 plus IL-2 failed to reconstitute the alloproliferative response. Of interest was the observation that preincubation of primary cultures of myocytes or the W1 cell line (especially after pretreatment with interferon-gamma) with an autologous enriched population of adherent cells, containing monocytes/macrophages/B cells, markedly augmented the ability of these cells to induce alloproliferative responses. In addition, the specificity of the secondary response of T cells primed against myocytes or the W1 cell line (especially after pretreatment of the myocytes or the W1 cell line with interferon-gamma) appeared to reside at the MHC type of the adherent cells used in the primary phase. These data suggest that adherent cells most likely present donor myocyte-specific MHC or other proteins to allogeneic T cells in the context of the MHC molecules of the adherent cells. Such a finding provides evidence that the indirect pathway of host cellular sensitization may occur in vivo and play a role in chronic graft rejection.

Antigen-Presenting Cells↗

PubMedDate not supplied

Cellular and molecular mechanisms of human cardiac myocyte injury after transplantation.

BACKGROUND: Fetal human cardiac myocytes or a cell line derived from fetal human cardiac myocytes, termed W1, even after experimental induction of "normal" levels of major histocompatibility complex class I and II antigens, fail to induce the activation of primary allogeneic responses. Therefore, our laboratory has investigated the ability of such MHC-expressing cardiac myocytes to induce secondary alloproliferative responses or to serve as target cells for cytotoxic T lymphocytes. METHODS: Cloned CD4+ and CD8+ T-cell lines having specificity for major histocompatibility complex class I and II molecules expressed by the fetal human cardiac myocytes and the W1 cell line were used in standard proliferation and cytotoxicity assays. RESULTS: Our data show that none of the 19 HLA-DR3 (beta 1 0301)- or HLA-DR15 (beta 1 1501)-specific CD4+ cloned T-cell lines reacted with HLA-DR3- or DR15-expressing W1 or fetal human cardiac myocytes. However, these CD4+ T cells did react, as expected, with similar HLA-DR3/DR15-expressing homozygous typing cells. Of the 16 cloned CD8+ cytotoxic T lymphocytes with specificity for HLA-A2 and the 12 with specificity for HLA-A1, only two of each showed weak cytotoxicity against interferon gamma-pretreated HLA-A2 and A1-expressing W1 and fetal human cardiac myocytes, respectively. Each cloned cytotoxic T lymphocytes line, however, was very effective against HLA-A2 and A1-expressing homozygous typing cells. Although the IFN-gamma-induced W1 and fetal human cardiac myocytes were not susceptible to cytotoxic T lymphocytes-mediated lysis, they were capable of inhibiting specific cytotoxic T lymphocytes function as defined by cold target inhibition studies. CONCLUSIONS: These data suggest that peptide-allo major histocompatibility complex presented by human cardiomyocytes is recognized by T cells and the these lymphocyte/myocyte interactions lead to immunologic ignorance.

CD4-Positive T-Lymphocytes↗