The age-related changes in the incidence of 'natural' anti-sperm antibodies suggest they are not auto-/isoantibodies

PROBLEM: Establishing the age-dependent patterns of sperm antibody levels among normal humans. METHODS OF STUDY: Sera samples from 498 healthy subjects aged 0-97 years - 246 males and 252 females - were tested by the gelatin agglutination test of Kibrick, tray agglutination test of Friberg, sperm immobilization test of Isojima and enzyme-linked immunosorbent assay (ELISA). RESULTS: We found a significant increase in the level of sperm agglutinins after 40 years, which decreased after 88 years. The antibodies detected by ELISA were the highest among prepubertal subjects and also declined with aging. No age-dependent changes were established for the sperm immobilizins. With few exceptions, there were no significant differences between male and female sera, as well as between sera of newborn and their mothers. CONCLUSIONS: These data are similar to those established for the age-dependent changes of antibodies towards exogenous antigens, suggesting that the 'naturally occurring' antibodies against human spermatozoa are not auto-/isoantibodies.