The nature of secretory agglutinins and aggregating factors. I. Secretory conglutinin-like factor, secretory bacterial aggregating factors and secretory IgA antibody in human saliva and amniotic fluid.

Secretory conglutinin-like factor (SKF), secretory bacterial aggregating factors (SBAF) and 11S secretory IgA antibodies of human saliva and full term amniotic fluid were quantitated by microtitration and partially characterized. The SBAF of both saliva and amniotic fluid aggregated a variety of oral streptococci, but no secretory IgA antibodies were found in amniotic fluid. The SKF and SBAF are distinguished from 11S IgA antibodies by being inhibited with EDTA and by being more susceptible to inhibition with reducing agents. These active factors are also distinguished from submaxillary mucins. Components of normal serum inhibit both SKF and SBAF, but blood-group reactive sugars cannot block either SKF or SBAF.