[Phenotypic and functional study of natural killer lymphocytes in flow cytometry: application to renal...

In order to define the best appraisal of Natural Killer cells, the authors performed a dual study, including both phenotypes and functional activities, and all the analyses were achieved with flow cytometric techniques. Results were applied to renal transplantation. Among the numerous clusters of differenciation, only CD16 and CD56 appeared to be well correlated with the functional properties of Natural Killer cells, and especially for CD3- cells. On the other hand, CD57 should no longer be considered as a NK marker. Functional properties of Natural Killer cells were evaluated by cytotoxicity assays of peripheral lymphocytes against K562 and Daudi tumor cells, either spontaneously, or after a 3-day activation with Interleukin 2 (LAK). The authors use carboxyfluoro-diacetate to label viable cells and avoid radioisotopes. They confirm the Natural Killer cells deficiency in renal transplant recipients, and show that this impairment also involves the LAK cytotoxicity. Azathioprine appeared to be responsible of such deficiency. During viral infections, Natural Killer cells raised and reached the normal values, while they were incapable of any response to fight against cancer. They suggest that the Natural Killer deficiency could explain the high incidence of malignancies during renal transplantation.