Possible role of the plasminogen receptor as a site of interaction of the human immunodeficiency virus p24 immunosuppressive heptapeptide Ch7 with the host immune system

Previous work from our laboratory demonstrated that a synthetic heptapeptid e (Ch7: RGSDIAG), corresponding to a conserved sequence of human immunodefi ciency virus (HIV) core protein p24 (amino acids 232-238), was able to spec ifically abrogate antigen-induced responses in cultures of normal human per ipheral blood mononuclear cells (PBMC), probably acting at the level of mon ocytes. The Ch7 peptide displays sequence homology to human plasminogen. In the present report we show that a compound (6-aminoexanoic acid), known to prevent plasminogen binding to monocyte-like cells, greatly reduced the im munosuppressive capacity of Ch7. We suggest that the plasminogen receptor m ay represent a target structure on human monocytes for the immunosuppressiv e p24 sequence.