Cell-mediated immune response in human hepatic echinococcosis. Analysis of antigen-induced lymphoproliferation and NK activity.

In vitro cellular immune responsiveness was studied in 25 patients undergoing surgery for hepatic hydatid disease and in 22 matched healthy controls. Proliferation of peripheral blood mononuclear cells (PBMC) induced by phytohaemagglutinin (PHA) was not statistically different in the two groups, while proliferation induced by antigenic preparations obtained from the human commensal microorganism Candida albicans was depressed in patients as compared to healthy subjects. Confirming previous data, antigen specific proliferative response to hydatid cyst fluids was greatly enhanced in patients as compared to controls (P less than 0.01). On the other hand, natural killer (NK) activity was significantly reduced (P less than 0.005). Both impairment of NK activity and lymphoproliferation induced by commensal microorganisms suggest that patients following the parasitic infection present a condition of relevant hyporesponsiveness in cell-mediated defence.