Inhibition of lymphoproliferation by a synthetic peptide with sequence identity to gp41 of human immunodeficiency virus type 1.

Peptides were synthesized that contained sequences from two regions (env amino acids [aa] 581 to 597 and 655 to 671) of the transmembrane protein gp41 and one region of the external envelope glycoprotein gp120 (aa 457 to 464) of human immunodeficiency virus type 1. Selection of these sequences was based on their homology to the highly conserved and immunosuppressive sequence contained within the transmembrane proteins p15E and gp21 of animal and human retroviruses, respectively. Peptide aa581-597 was found to specifically inhibit human and murine lymphoproliferation, whereas peptides aa655-671 and aa457-464 had no activity. These results suggest a mechanism by which human immunodeficiency virus type 1 gp41 exerts a direct immunosuppressive effect in vivo, analogous to that postulated for p15E and gp21, which could contribute to the immune dysfunction observed in patients suffering from acquired immunodeficiency syndrome. It is of particular interest that the sequence aa 584 to 609, shown to contain B- and T-helper-cell epitopes, overlaps with the sequence aa 581 to 597 that is shown here to inhibit lymphoproliferation. The potential implications of this overlap of immunologic activities are discussed.