Comparative study of Cyclomunine and Cyclosporin A on human lymphocyte proliferation in vitro. The lack of an immunosuppressive effect by specific clonal deletion.

The effect of Cyclomunine (Cym) and Cyclosporin A (CyA) on in vitro human lymphocyte proliferation was assessed and it was noted that Cym and CyA suppressed lymphocyte response to mitogens, allogeneic cells or antigen in a dose--and time--dependent fashion. Furthermore, using a secondary mixed lymphocyte reaction model, we showed that neither CyA nor Cym exerted their immunosuppressive activity by producing specific clonal deletion and that their constant presence was necessary to obtain an antilymphocytic activity. These data suggest that treatment with these drugs in allotransplantation should be on a continuous basis.