INHIBITION OF PHAGOCYTES BY CYCLOSPORINE IN-VITRO

Cyclosporin is an immunosuppressant that acts by selectively inhibitin g the activation of T lymphocytes. Its effects on monocytes and neutro phils are not well explored. We investigated the in vitro effects of c yclosporin on these cells, harvested from venous blood from nine healt hy, nora-smoking volunteers. In vitro incubation of monocytes with inc reasing concentrations of cyclosporin (5, 25 and 625 mu g) depressed t heir phagocytosis by 22%, 32% and 49%, respectively, compared to the c ontrol values. The intracellular killing capacity of monocytes decreas ed by 26%, 31% and 43% with these doses, and neutrophil phagocytosis w as depressed in a similar manner (16%, 30% and 40%). Patients receivin g cyclosporin are susceptible to infections, and inhibition of these p hagocytic cells by cyclosporin may be partly responsible for this. Neu trophil chemotaxis is reduced in patients with impaired renal function . Treating these patients with cyclosporin may in addition suppress th e phagocytic function of these cells.