Decrease in natural killer cell activity in kidney allograft recipients

The natural killer cell activity (NKCA) of a population of 66 functioning kidney allograft recipients (followed up for over 9 years) was assessed on K562 and DORA cell line targets. The 51Cr specific release test showed a rapid, sharp decrease in NKCA as early as 3 months after grafting, reaching a minimal level between 7 and 60 months (5 +/- 5 vs. 45 +/- 19% 51Cr release; P less than 0.001). Patients showing an almost total lack of NKCA were roughly the same whether assessed on K562 or DORA targets. NKCA tended to be restored in long-term transplanted patients (greater than 61 months). Control populations, aside from 32 healthy individuals, consisted of 11 haemodialysed patients as well as patients submitted to corticosteroid therapy for more than one year (8 cases of giant cell arteritis and 4 chronic asthmas). Haemodialysed patients exhibited normal NKCA (whether previously grafted or not). Corticosteroid-treated patients showed either no significant modification (K562 target) or a borderline decrease (DORA target) in NKCA. Azathioprine or corticosteroid dosage intake on the day of the test did not influence the level of graft recipient NKCA. The natural cytotoxicity of peripheral blood lymphocytes (PBL) from recipients lacking in activity (less than 5% 51Cr release) was not restored by exogenous (type alpha) interferon. and PBL of recipients with low NKCA scores produced normal levels of purified interferon after 24-h Sendai virus exposure. No inhibitory effects of sera obtained from recipients lacking NKCA nor any active suppressor cells from their PBL could be evidenced, thus suggesting an actual loss of natural killer progenitors (or an "insensitivity" to interferon) in those patients. Corticosteroids, as opposed to azathioprine, were able to decrease the in vitro NKCA of healthy donor PBL at pharmacological concentrations.