Antibody reactivity with porcine zona pellucida

A comparative study on anti-zona antibody activities in the sera from clinically defined categories of patients registered at the WHO Reference Bank for Reproductive Immunology was performed at five different laboratories with different detection methods. Considerably higher incidences of positive reactions were detected by immunofluorescence on porcine zonae in infertile women (16.3%) than in control subjects (7.1%). A similar proportion of positives was found by radioimmuno-binding assay (RIBA) using porcine zona antigen preparation in the infertile group (13.0%) but not in the female control group (0%), giving an indication of the specificity of this test. It is noteworthy that high incidences of positives were observed by RIBA with sera from male subjects with unexplained sterility, vasectomy and aspermatogenesis. A test system of passive hemagglutination reaction (PHAR) using purified porcine zona substance as antigen gave a low but slightly higher incidence of positives in infertile (3.1%) than in control sera (0.9%). No positive reactions were observed with infertile and control sera by another PHAR or by radioimmunoassay using an antigen preparation common to the two test systems. Anti-zona activities in these sera were therefore seen to vary, depending largely upon the detection systems and the antigen preparations.