MEMBRANE GLYCOLIPIDS AND HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION OF PRIMARY MACROPHAGES

The membrane glycolipids galactosylceramide (GalCer) and sulfatide (SG alCer) have been reported to act as receptors of human immunodeficienc y virus (HIV) on CD4(-) cell lines, We show here that these glycolipid s are present on CD4(+) cells purified from human blood and on in vitr o-differentiated monocyte-derived macrophages (MDMs). We investigated the role they could play in HIV infection, Glycolipids of MDMs were ch aracterized at the molecular level by immunolabeling and thin-layer ch romatography immune overlay, using a panel of human-, rabbit-, or muri ne-specific antibodies, GalCer and SGalCer were expressed at the surfa ce of MDMs as assessed by indirect immunofluorescence and flow cytomet ry analysis, and they could be characterized with specific antibodies in the cellular glycolipid extracts in addition to GM1, GM3, and GD1b gangliosides. Recombinant I-125-labeled gp160 specifically bound to Ga lCer, SGalCer, GM1, and GM3 as well as to phospholipids (phosphatidyle thanolamine and phosphatidylserine) from MDM extracts, Anti-SGalCer mo noclonal antibodies (MAbs), but not anti-GalCer antibodies, entailed l imited (30-40%) but significant inhibition of gp160 binding to MDMs. H owever, the four human anti-SGalCer MAbs and the three murine or rabbi t anti-GalCer antibodies tested did not inhibit HIV infection of MDMs, in contrast to CD4 antibody anti-Leu3a tested in parallel. These find ings suggest that, although HIV envelope glycoprotein can bind to SGal Cer and GalCer from CD4(+) MDM extracts, these glycolipids do not appa rently act as HIV coreceptors nor are they involved in HIV infection o f these cells.