Asymptomatic females: detection of antibody activity to gonococcal pili antigen by radioimmunoassay.

A gonococcal pili antigen preparation was used to detect antibody activity sera obtained from 322 culture-positive asymptomatic females and 150 negative controls. Pili were obtained from a culture of type 2 Neisseria gonorrhoeae (strain 2686) and labeled with 125I for use in a double-antibody radioimmunoassay test system. Of the 322 sera obtained from culture-positive, asymptomatic females, 276 (85.7%) showed antibody activity greater than or equal to 1.8 mug/ml. Negative controls were obtained from three different groups of individuals, and 130 (86.7%) had undetectable antibody activity. Sera from asymptomatic, culture-positive females were absorbed with three different strains of N. gonorrhoeae, one of these strains being the organism used for pili antigen preparations. The absorbed sera were tested for antibody activity, and in each case the activity in the absorbed sera dropped to an undetectable level. When the same sera were absorbed with N. meningitidis, N. catarrhalis, N. perflava, Escherichia coli, Herellea vaginicola, Mima polymorpha, Staphylococcus aureus, and Candida albicans, little, if any, decline in the level of anti-pili antibody activity was observed.