Human suppressor T cells induced in vitro with an autologous renal allograft-derived T cell line I. Suppressor cell induction, function, and specificity

The functional characteristics of T suppressor (Ts) cells generated from the peripheral blood lymphocytes (PBL) of a kidney transplant recipient who had excellent graft function for 1 year were examined. Ts cells were induced by co-culture of PBL with an autologous alloreactive cytotoxic T lymphocyte (CTL) line (EE-1) previously grown from a routine renal allograft biopsy of this patient performed 10 days posttransplant. The EE-1 line included CD3⁺ T cells of CD8⁺ and CD4⁺ phenotypes with cytotoxic specificity for disparate class I (HLA-B8) and class II (HLA-DR1 and 3) antigens of the kidney donor (JC). The EE-1 induced Ts cell lines (designated TsEE) were found to significantly suppress (50%-95%) autologous fresh responder EE-PBL stimulation by donor EBV-transformed cells (JC-EBV) in mixed lymphocyte reaction (MLR) assay. TsEE cells were CD3⁺ (98%) and predominantly CD8⁺ (68-80%), showed no cytotoxic activity, and were suppressive only at the early phase of MLR stimulation. In three-party cell test MLR assays, TsEE-mediated suppression appeared restricted to responder cells sharing HLA-B7 with the suppressor line, and was not abrogated by the addition of exogenous interleukin-2 (IL-2). TsEE cells also showed restricted suppression of CTL generation but not mature CTL activity. The restricted suppressor activity of TsEE lines was dependent upon their induction and restimulation with the autologous EE-1 line.