Studies have shown that platelet-lymphocyte complex formation increases during HIV-1 infection (7, 29) and that the P-selectin glycoprotein ligand-1 (PSGL-1) on CD4+ T cells and P-selectin (CD62P) on platelets expressed after platelet activation mediate the interactions between platelets and lymphocytes (16). This evidence concerns the gene CD4 and HIV-1 infection.