Cytochemical detection of receptors specific for N-linked oligosaccharides of glycoproteins in the membrane of the human spermatozoon and their distribution in the different zones of that membrane

Adherence of Escherichia coli to sperm: a mannose mediated phenomenon leading to agglutination of sperm and E. coli

OBJECTIVE

To investigate the mechanism of adherence between Escherichia coli and sperm.

DESIGN

Experimental study performed with donor sperm and male genital tract-derived E. coli.

SETTING

Andrology unit of a university hospital.

PATIENTS

None.

INTERVENTIONS

Monitoring of sperm-E. coli agglutination; addition of sugars to block adherence; electron microscopy.

MAIN OUTCOME MEASURE

Sperm-E. coli agglutination.

RESULTS

Escherichia coli readily adhered to and agglutinated sperm. The phenomenon was observed at E. coli to sperm ratios as low as 1:20; maximum sperm agglutination involving approximately 90% of spermatozoa was seen with ratios of 1:5 or higher. By transmission electron microscopy, E. coli adherence was observed both on sperm heads and tails. Heteroagglutination could be blocked by D-mannose and alpha-methyl-mannopyranoside but not by other sugars. Preincubation of sperm or E. coli with mannose resulted in block of agglutination, indicating mannose-binding structures both on sperm and E. coli.

CONCLUSIONS

Adherence of E. coli to sperm is mediated by mannose and mannose-binding structures present on both cell types. Agglutination of sperm by E. coli may be relevant in male and female infertility.

Detection of a sperm-coating antigen in the semen of Bubalus bubalis

1. Surface antigens of B. bubalis spermatozoa were solubilized by Triton X-100 and EDTA; the sperm extract was used to raise antibodies in rabbits. 2. Two major polypeptides, immunoprecipitated from the seminal plasma by the antibodies against the sperm extract, exhibited the same electrophoretic mobilities of two immunorelated sperm surface antigens. 3. The two polypeptides were isolated from the seminal plasma, by a multi-step chromatographic procedure, and found subunits of a single protein (MW 30,000), called SP 30. 4. The SP 30 protein bound in vitro to the postacrosomal region of homologous spermatozoa from cauda epididymis. 5. The localization of the sperm-coating antigen on the cell surface is compatible with a role in the fertilization process.

Failure to detect integrins of the beta-2 subclass on the human sperm surface

Several cell-to-cell recognition systems utilize the tripeptide Asp-Gly-Arg (RGD) as a cell surface signaling sequence. Mac-1, a member of the integrin subfamily defined by the beta-2 subunit, recognizes C3bi by means of an RGD sequence. Because C3 complement components have been detected on the gamete surfaces and RGD has been demonstrated to be involved in sperm-egg interaction, we explored the possibility that a member of the b2 integrin subfamily was present on the sperm surface and involved in egg recognition. Two methods were utilized to detect integrins on the sperm surface. Sperm were exposed to Mabs directed against different epitopes of each member of this integrin subfamily; and spermatozoa were tested for their ability to bind zymosan or yeast, since Mac-1 bearing cells possess this property. Both methods failed to demonstrate such integrins on the sperm surface, suggesting that another RGD receptor is involved in gamete recognition.