Direct evidence for uptake of 2D6-reactive antigens from epididymal secretions was obtained by incubating proximal caput spermatozoa (which do not bind 2D6 McAb) in vitro with caudal fluid. Since neither rat erythrocytes nor lymphocytes stain positively with 2D6 McAb after incubation in caudal plasma, it suggests that uptake is cell-type specific and mediated either by a specific receptor or by unusual properties of the plasma membrane of spermatozoa. dexone tablets
Both these possibilities could also account for the fact that uptake of 2D6 in vitro is not species specific since mouse (and hamster, results not shown) spermatozoa absorb significant amounts of the antigen. It is of interest that regardless of the species, uptake of 2D6 antigens in vitro mimics that found in vivo as they bind to the tail plasma membrane with a characteristic patchy appearance. Uptake in vitro is unaffected by prior dialysis of the CEP or by the presence of high salt or reducing reagents, suggesting that the interaction with the plasma membrane is primarily hydrophobic. This conclusion is further supported by the finding that only detergents are effective in solubilizing the 24-kDa antigen from mature cauda spermatozoa, and in phase separation experiments, —50% of it partitions into Triton X114.