Tissue distribution of T-lymphocytes and Ia-expressing cells in rat kidney grafts

In a rat kidney transplantation model, DA kidneys were transplanted into Lewis rats. Syngeneic Lewis transplantations were studied as controls. Histologic evaluation was made, and immunohistochemical staining with a single-staining peroxidase-antiperoxidase technique on frozen sections was performed after 2, 4, 6, and 8 days. Antibodies for Ia antigen (Ox 6), 'suppressor/cytotoxic' cells (Ox 8), pan-T cells (W 3/13), and 'helper/inducer' cells (W 3/25) were used. Allogeneic grafts were almost completely rejected in 8 days. Syngeneic grafts also showed lymphocyte infiltrates, somewhat later than allogeneic ones, but were not rejected. In these infiltrates W 3/25-positive cells dominated, being even more numerous than W 3/13-positive cells. Relatively fewer Ox 8-positive cells were seen in the infiltrates of syngeneic than in allogeneic transplants. Infiltrates occurred later in the renal medulla than in the cortex. Perivascular infiltrates with cells of all investigated phenotypes were seen earlier in allogeneic grafts than in syngeneic ones. All tubular cells within one renal tubule appeared either Ox 6-positive or -negative. With time, all tubules in the allogeneic transplants became Ox 6-positive. Some increase of Ox 6-positive tubules was also seen in syngeneic transplants.