Natural killer-cell activity, interferon-alpha 2 production, and interleukin-2 production in cyclosporine-treated and conventionally immunosuppressed human allograft recipients.

Natural killer (NK) activity, interferon (IFN)-alpha production, and interleukin-2 (IL-2) production were measured in renal transplant recipients undergoing immunosuppression with either azathioprine and steroids (Az + P) or cyclosporine (CyA). Overall, both IFN-alpha production and IL-2 production were impaired in these two groups compared with identical studies in healthy individuals. However, on the basis of control data these two patient groups were divided into those with "normal" NK activity and those with "low" NK activity. In the CyA group those with a low NK reaction produced less IL-2 and IFN-alpha than those with normal NK activity. No such relationship between cytokine production and NK activity was discerned in the Az + P group. These data conflict with in vitro studies, which have failed to demonstrate any effect of CyA on IFN-alpha production. In addition, they suggest that whereas cyclosporine influences NK activity in vivo by inhibiting cytokine production, other factors may play a role in impairing NK activity in conventionally immunosuppressed patients.