Analysis of T cell lines from rejecting renal allografts

Acute rejection after renal allotransplantation is characterized by the presence of a mononuclear cell infiltrate in the interstitium with involvement of tubuli. In a previous study on renal histology we showed that tubular damage by graft infiltrating cells (GIC) is a sign of clinically significant rejection. We cultured proximal tubular epithelial cells (PTEC) and T cells bearing the interleukin 2 (IL-2) receptor from biopsies after transplantation. In vitro outgrowth of T cells from the biopsy was significantly (P = 0.0014) related to histological signs of graft rejection. Of the T cell lines generated from 25 biopsies, only five lines showed no or low cytotoxicity against donor PTEC. Three cell lines were cytotoxic towards donor PTEC, but not against PHA stimulated donor splenocytes, suggesting tissue specificity of GIC. Treatment of PTEC with interferon (IFN) gamma for 72 hours to upregulate MHC class I and to induce MHC class II expression did not necessarily result in an increased susceptibility to lysis. However, three PTEC lines displayed an increment of susceptibility to lysis after IFN gamma treatment. Analysis of one T cell line from the same graft revealed a high percentage of CD4 positive cells, compatible with a class II restricted cytotoxicity. This was confirmed by blocking experiments using anti-CD4, anti-CD8, anti-class I, and anti-class II antibodies. Blocking experiments were done with 12 of these 25 lines. Anti-CD3 and anti-CD18 antibodies inhibited cytotoxicity in every case, showing that cytotoxicity was T cell mediated.(ABSTRACT TRUNCATED AT 250 WORDS)