Inhibition of HIV Type 1 Infection of Mononuclear Phagocytes by Anti-CD44 Antibodies

Cellular CD4 is the primary membrane molecule that binds HIV-1 through interaction with viral gp120. Membrane glycolipids and cell adhesion molecules have also been noted to be involved in the interaction of HIV-1 with cells and in syncytium formation in infected cells. The purpose of this study was to determine the role of the cell adhesion molecule CD44 in HIV-1 infection of cells. Both normal blood monocytes and lymphocytes expressed CD44 as determined by flow cytometry using the anti-CD44 antibody A3D8. Anti-CD44 monoclonal antibodies A3D8, A1G3, and 5F12 [ascites, purified IgG, and F(ab')₂] inhibited infection of monocytes and peritoneal macrophages with HIV-1-BaL and HIV-1-ADA, but had no effect on HIV-1-IIIB infection of mitogen-stimulated lymphocytes, or cells of a T lymphocyte line. CD44 monoclonal antibodies were not toxic for monocytes, and the observed inhibitory effect of CD44 monoclonal antibodies was not dependent on complement. These results suggest that CD44 may be a determinant of HIV-1 infection of mononuclear phagocytes in vitro.