Autoantibodies to zona pellucida in infertile and aged women.

A total of 735 human serum samples were tested against isolated porcine ova for detection of autoantibodies to zonae pellucidae by the specific method reported previously using indirect immunofluorescence. Positive fluorescence was found in 13 of 175 samples (7.4%) from patients with unexplained infertility, in 2 of 122 samples (1.6%) from patients with proven etiology of infertility, but in none of 141 samples from age-matched control subjects (fertile women and men). There was an age difference in the incidence of positive reactions: 4 of 156 samples (2.6%) from women over 40 years old were positive in contrast to only 1 of 159 samples (0.6%) from women under 40 years old. Although autoantibodies to zonae pellucidae may be produced during the aging process, the observed high incidence in unexplained infertility suggests an etiologic association of the antibody with the disease when produced in younger women.