DYNAMICS OF MONOCYTES MACROPHAGES AND T-LYMPHOCYTES IN ACUTELY REJECTING RAT RENAL-ALLOGRAFTS/

We examined the infiltration of acutely rejecting renal allografts (DA -->LEW) by ED1(+) and ED2(+) macrophages and T lymphocytes at interval s of 24 h after transplantation. Donor and recipient macrophages were differentiated by MHC class II antigen expression in double-staining e xperiments with ED1. Proliferation was assayed after pulse-labelling w ith BrdU. We subdivided allograft infiltration into three consecutive phases: 1) During phase I on days 1 to 2 after allogeneic kidney trans plantation, perivascular infiltrates developed that contained numerous donor and recipient macrophages. Allograft rejection could already be diagnosed 24 h after transplantation by perivascular infiltration of T lymphocytes, whereas T cells were rarely found in isografts. 2) Phas e II of allograft rejection from day 3 to 4 was characterized by massi ve propagation of the infiltrate. About equal numbers of interstitial donor and recipient macrophages were counted. Both macrophages and T l ymphocytes proliferated in situ and macrophages outnumbered T cells un til complete rejection. 3) During phase III the allograft was destroye d. Large intravascular monocytes surprisingly expressed the ED2 antige n. In the interstitium of viable graft regions, the population of reci pient macrophages grew, whereas the population of donor macrophages an d of T lymphocytes decreased.