Disintegration of human spermatozoal membranes in seminal plasma decreases the binding capacity of integrins

The in vitro binding capacity of spermatozoal integrins to matrix components after disintegration of sperm membranes was evaluated. The percentage of spermatozoa with functionally-relevant integrins was determined before and after devitalization of spermatozoa, which were resuspended in seminal plasma or in culture medium. The devitalization was performed by cryoshock or by incubation of spermatozoa with triton X-100 in a concentration ranging from 0.01 to 1.0%. The spermatozoal integrins were detected by the binding of anti-integrin antibodies and flow cytometry and the functional activity was monitored by the binding of the spermatozoa to the matrix components in a cell attachment assay. The seminal plasma decreased the binding of anti-integrin antibodies to the spermatozoal surface and the binding of spermatozoa to ligands and matrix components. respectively. In contrast, the expression of fibronectin and laminin on spermatozoa was increased. Not all spermatozoa, which expressed integrins on their surface bound to the ligands in the cell attachment assay. These results suggest that the detectable integrins only partially exert functional relevance. It can be concluded that the spermatozoa with fragile plasma membranes are more prone to functional inactivation of their integrins by the seminal plasma.