[Natural cell-mediated cytotoxicity of kidney allograft recipients].

Natural cell-mediated cytotoxicity (NCMC) displayed by peripheral blood mononuclear cells of kidney allograft recipients was examined against K562 cells to demonstrate the kinetics of NCMC activity in the posttransplant period. On 44 kidney allograft recipients 301 NCMC assays were performed between 1 and 84 months after transplantation. These patients were treated with the conventional immunosuppressive treatment consisting of steroid and azathioprine. NCMC activity sharply decreased after transplant surgery. A decreased NCMC activity continued during the first 6 months and the mean NCMC value was 19.2 +/- 14.1. In the second 30 months, NCMC activity also constantly decreased, almost to 10. It was lower than that of the first 6 months (P less than 0.01). After 37 months, some patients restored a normal NCMC activity and others showed a decreased NCMC activity. The mean value was 27.4 +/- 20.6 in the third 48 months. The depression of NCMC activity might be caused by the large dose of steroid and azathioprine in the first 6 months. In the third 48 months, NCMC activity might be dependent on the dosage of azathioprine alone. The activation of NCMC activity might be caused by acute rejection crisis.