Antibodies to human spermatozoa impede sperm penetration of cervical mucus or hamster eggs

Antisperm antibodies from infertile patients and men with vasectomies can impede human sperm penetration of hamster eggs. When human spermatozoa were exposed to antisperm antibodies, six samples totally blocked and another ten significantly reduced sperm penetration, and only two samples yielded results comparable with those obtained with normal serum. The penetration rate was 59% for the control sera; the test serum rate was 15%. Ninety percent caused a reduction in egg penetration. The IgG fraction caused a reduction similar to that of whole serum. Antisperm antibodies can also reduce sperm penetration of cervical mucus. We found that 21% of the serum samples reduced mucus penetration. No specific antisperm antibody type (agglutination, immobilization, or antibodies as revealed by immunofluorescence) always prevented cervical mucus penetration or sperm penetration of hamster eggs. Furthermore, exposure to even high titers of antibodies in some serum samples did not result in total prevention of sperm penetration either of hamster eggs or cervical mucus, an indication that only certain antibody types prevent chances of fertility. The use of sperm penetration assays may be valuable tools with which to determine (1) the fertilizability of semen from men who exhibit seminal antisperm antibodies and (2) the importance of various antibodies in the prevention of fertilization.