The specificity in the mixed lymphocyte kidney culture (MLKC) of T cell lines and clones derived from human end-stage renal disease (ESRD) kidneys was studied using collagenase dispersed kidney cells compared with lymphocytes as stimulating cells. These experiments were performed because of previous studies in which infiltrating lymphocytes freshly isolated from ESRD kidney tissue at nephrectomy (as well as autologous splenic T cells) were seen to directly generate this lymphoproliferative MLKC response when stimulated with autologous renal cortical cells. In the current studies, histopathologic staining of tissues and suspensions of infiltrating kidney lymphocytes showed predominance of OKT4 labeled phenotypes, and the stimulation indices in MLKC in general showed a direct relationship with the percentage of helper cells seen in the infiltrates. When T cell lines and clones derived from lymphocytes infiltrating the ESRD kidneys were tested in MLKC, there was evidence of kidney-associated, as opposed to lymphocyte-associated (MLC) reactivity using (3H) thymidine uptake as a reflection of a lymphoproliferative response. Several cell lines and clones derived from these T lymphocytes exhibited a dual reactivity. They served as responding cells in the MLKC reaction and completely suppressed a non-specific allogeneic MLC when added as third-party cells. Quantitatively, some clones suppressed when third-party x-irradiated cells were only 5% of the responding cell number in coculture. In addition to the dual reactivity, phenotypic analysis of these same cell lines and clones employing monoclonal antibodies revealed that individual cells expressed both OKT4 and OKT8 determinants. However, ∼90% of the cells in the MLC enhancing line were labeled with OKT4. These results indicate that there is a complexity in the autologous MLKC response in that cells with both helper/inducer and suppressor/cytotoxic function take part in the reaction. Although delayed-type hypersensitivity to kidney-associated antigens is inferred as a result of these in vitro assays, nonspecific suppression of other Ia-dependent reactions can simultaneously occur.
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