Human sperm and spermatogonia express a galactoglycerolipid which interacts with gp120

Sexual transmission is a major mode of spread of HIV-1 although the mechanisms involved remain to be elucidated. The role of spermatozoa as carriers of the HIV is supported by recent publications, while the expression of the CD4 on the membrane of the sperm has not yet been demonstrated. The data reported in this paper show that a glycolipid molecule, most likely the galactosyl-alkyl-acylglycerol, structurally similar to galactosylceramides, is present on the surface membrane of the spermatozoa. Consistent with a structure similar to galactosylceramide, the sperm glycolipid is capable of binding the gp120 as demonstrated utilizing an improved ELISA assay which favors sensitivity and specificity. Immunocytochemistry of testicular tissue shows the presence of this glycolipid on the membrane of immature germ cells, preferentially in the spermatogonia. These data indicate that human sperm express a glycolipid similar in structure to the receptor for HIV described on the CD4- neural and colonic epithelial cell lines, and moreover suggest that this glycolipid could also function as HIV receptor and possibly be implied in its transmission. The demonstration that this molecule is also expressed by the spermatogonia suggests its involvement in the interaction of the HIV with spermatogonia, as recently reported, and could explain the inhibition of spermatogenesis observed in AIDS patients.