Administration of ATG according to the absolute T lymphocyte count during therapy for steroid-resistant rejection.

In renal transplantation, treatment of steroid-resistant rejection (SRR) with antithymocyte globulin (ATG) has been widely reported but over-immunosuppression remains a common problem. In the first ten patients (group 1) treated for SRR with rabbit ATG, three developed serious viral infections and two deaths occurred due to CMV pneumonitis. ATG was only omitted if thrombocytopenia or neutropenia occurred. In the next 17 patients (group 2) with SRR, ATG was administered according to the absolute T lymphocyte count. T lymphocytes were measured by flow cytometric analysis of CD3-labelled lymphocytes. ATG dosage was adjusted on a daily basis to keep the absolute T lymphocyte count under 50 cells/microliters. Administration of ATG according to the absolute T lymphocyte count resulted in a significant reduction in the mean dose of ATG given to the group 2 patients (P < 0.001). A significant decrease in the incidence of serious viral infections (P = 0.04) was achieved without reducing the ability of ATG to reverse the SRR (P = 0.29) or increasing the number of grafts lost at 1 year in the group 2 patients (P = 0.23).