INTERFERON-GAMMA (IFN-GAMMA) CAN COUNTERACT THE IN-VITRO INHIBITORY EFFECT OF AN HIV P24 IMMUNOSUPPRESSIVE HEPTAPEPTIDE

Previous work from our laboratory demonstrated that a synthetic heptap eptide (Ch7), corresponding to a conserved sequence of HIV core protei n p24 (aa 232-238), was able to specifically abrogate antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PB L). In the present study we show that Ch7 did not inhibit the inductio n of IFN-gamma-secreting cells nor the accumulation of IFN-gamma mRNA in antigen-stimulated cultures. However, delayed addition of recombina nt human IFN-gamma to Ch7-suppressed cultures was able to restore full y the capacity to mount an antigen-specific antibody response. Thus, a lthough the Ch7 immunosuppressive effect may not be directly related t o a decreased production of IFN-gamma, an increased level of this cyto kine is certainly able to counteract the negative effect of the peptid e.