Identification of the cellular subpopulations infiltrating rejecting cadaver renal allografts. Preponderance of the T4 subset of T cells.

In the rejection response against renal allografts, the relative importance of helper/inducer T cells mediating a delayed-type hypersensitivity response and of T cells with direct cytotoxicity has not been defined. These subpopulations were identified with commercially available monoclonal antibodies and an indirect immunoperoxidase technique in 31 renal biopsies from patients undergoing acute rejection episodes and in 9 rejected nephrectomy specimens. T lymphocytes were the predominant cell population in all biopsies and in 8 of 9 nephrectomies. The T4 helper/inducer subset was equal to, or greater than, the T8 cytotoxic/suppressor subset in 28 of the 31 biopsies and in the 8 nephrectomy specimens that had histological evidence of cellular rejection. T4 lymphocytes were found predominantly in large areas of cellular infiltrate. T8 lymphocytes had a more diffuse interstitial distribution and were a minority of the cells in the large areas of cellular infiltration. These results show that helper/inducer T lymphocytes are often more frequent than cytotoxic/suppressor cells in acute renal allograft rejection in humans and they suggest that helper/inducer T cells may play an important role in the mediation of graft destruction.