T-lymphocyte subsets and HLA-DR-expressing cells in rejected human kidney grafts

This communication describes an immunohistochemical analysis of rejected human renal allografts. T-lymphocyte subsets were identified in frozen tissue sections, by Leu 1 (anti-'pan' T lymphocytes), Leu 2a (anti-'cytotoxic/suppressor' T cells), and Leu 3a (anti-'helper/inducer' T cells) monoclonal antibodies. In addition, HLA-DR-positive cells were identified by simultaneous labelling with heterologous anti-HLA-DR antibodies. T cells dominated the cellular infiltrates in acute cellular rejection. Leu-3a-positive cells were more numerous than Leu-2a-positive cells. The Leu-3a-positive cells usually appeared in clusters, whereas the Leu-2a-positive cells appeared scattered in the tissue. HLA-DR-positive non-T cells were found within clusters of T 'helper/inducer' cells. The cell pattern shares many features with the findings in delayed-type hypersensitivity reactions.