Inhibition of human immunodeficiency virus infection of CD4+ cells by CD4-free glycopeptides from monocytic U937 cells.

We have previously demonstrated that human immunodeficiency virus (HIV) envelope glycoproteins have specific carbohydrate-binding properties for mannosyl/N-acetylglucosaminyl residues presented at high density on a carrier in vitro. Here, we investigated whether HIV envelope glycoprotein gp120 was able to interact with surface membrane carbohydrates of CD4(+) cells by means of such lectin-carbohydrate interactions, CD4-free tryptic glycopeptides, prepared from the membrane of CD4(+) monocytic U937 cells and partially purified by ConA-agarose affinity chromatography, could be eluted by mannan but not by methyl-alpha-mannose or methyl-alpha-glucose, which strongly suggests that they displayed oligomannosidic structures, These glycopeptides bound in a mannosyl-specific manner to radiolabeled recombinant gp120, Deglycosylation with N-glycanase which, as expected, strongly diminished binding of the glycopeptides to concanavalin A also abolished their interaction with gp120, In addition, the glycopeptides inhibited HIV infection of both U937 and CD4(+) lymphoid CEM cells when preincubated with the virus, These findings indicate that, independently of the binding to CD4, mannosyl structures on CD4(+) sells may play a role through lectin-carbohydrate interactions in envelope glycoprotein binding to a putative coreceptor(s) of HIV.