Interferon-gamma (IFN-γ) can counteract the in vitro inhibitory effect of an HIV p24 immunosuppressive heptapeptide

Abstract

Abstract Previous work from our laboratory demonstrated that a synthetic heptapeptide (Ch7), corresponding to a conserved sequence of HIV core protein p24 (aa 232–238), was able to specifically abrogate antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). In the present study we show that Ch7 did not inhibit the induction of IFN-γ-secreting cells nor the accumulation of IFN-γ mRNA in antigen-stimulated cultures. However, delayed addition of recombinant human IFN-γ to Ch7-suppressed cultures was able to restore fully the capacity to mount an antigen-specific antibody response. Thus, although the Ch7 immunosuppressive effect may not be directly related to a decreased production of IFN-γ, an increased level of this cytokine is certainly able to counteract the negative effect of the peptide.