Naturally occurring double-stranded RNA and immune responses. Effects on plaque-forming cells and antibody formation.

A highly purified preparation of double-stranded RNA, obtained from virus-like particles in Penicillium cultures, was found to affert humoral immune responses in mice differentially depending on its time of administration in realtion to antigen. Double-stranded RNA administered with antigen, or a few hours after antigen, produced a variable degree of enhancement of plaque-forming cell numbers or agglutinating antibody levels depending on the antigen involved. Administration of double-stranded RNA 24 hours before antigen invariably produced a suppressed response. In mice which were either specifically hyporesponsive (tolerant) or non-specifically hyporesponsive (due to age or immunosuppressive drugs) double-stranded RNA administered with antigen resulted in a nearly normal immune response.