In-vitro effects of cyclosporin A, FK506, 6-mercaptopurine, and prednisolone on lymphokine-activated killer cells.

In transplant recipients, immunosuppressive regimens are deleterious on natural killer (NK) and lymphokine-activated killer (LAK) cells, which beyond their well-known antitumoral activity display many important biological functions. In order to find which regimens could preserve NK and LAK functions we tested the influence of CsA, FK506, 6-mercaptopurine and prednisolone on HLA-unrestricted cytotoxicity during an in-vitro IL-2 activation. For each drug we obtained peripheral blood samples from 11 healthy volunteers. Non-adherent PBMC were incubated 2 days with either CsA, FK506, 6-mercaptopurine or prednisolone, whose concentrations ranged from 0 to 10 micrograms/ml, in order to screen infratherapeutic, therapeutic, and supratherapeutic doses. Thereafter, 100 IU of IL-2 were added for a further 3-day culture. Before and after the culture, we analysed (1) the cell subsets by direct immunofluorescence staining with anti-CD3/CD16/CD56 antibodies, (2) the LAK activity with the lysis of Daudi cells, (3) the cell proliferation with a 24-h incorporation of thymidine. Cyclosporin and FK506 did not impair the LAK cytotoxicity nor the number of LAK cells, whereas both prednisolone and 6-mercaptopurine decreased the LAK cytotoxicity, the number of CD3- CD16+ CD56+ cells, and the thymidine uptake. As a whole, the LAK cytotoxicity was correlated with the number of CD3- CD16+ CD56+ cells but not with the number of CD3+ CD16- CD56- cells, and it also increased with the incorporation of thymidine. This latter was correlated with the number of CD3- CD16+ CD56+ cells, but not with the number of CD3+ CD16- CD56- cells.(ABSTRACT TRUNCATED AT 250 WORDS)