Interleukin 2 receptor expression in renal biopsies and the diagnosis of acute allograft rejection.

The aim of the study is to test the diagnostic usefulness of assessing interleukin 2 receptor (IL2R) expression in infiltrating lymphocytes in renal biopsies from patients with suspected acute renal allograft rejection and to compare the NIH-CCTT and the Banff 97 systems of classifying the histopathologic changes in acute renal allograft rejection. The expression of interleukin 2 (IL2) and IL2R, as shown immuno-histochemically, is the final step in T cell mediated acute renal allograft rejection. Renal biopsies obtained from 40 patients clinically suspected to have early acute allograft rejection were examined histologically to diagnose acute allograft rejection and classified by the two systems. Frozen sections of the biopsies were stained with specific antibody for the presence of IL2R. 31 of the 40 patients were histologically and clinically confirmed to have acute allograft rejection. There was significant correlation with this diagnosis and the demonstration of IL2R on infiltrating lymphocytes. The CCTT system of grading correlated better with the presence of IL2R and the confirmed diagnosis of acute allograft rejection. The immunohistochemical demonstration of IL2R is a useful adjunct in the evaluation of biopsies suspected to show changes of acute cellular rejection. Since IL2 expression reflects the relative proportion of activated lymphocytes in the cellular infiltrate, it is proposed that the degree of IL2 expression may reflect the response of the use of monoclonal antibodies (Humanised/Chimaerised) as anti rejection therapy.