The nature of secretory agglutinins and aggregating factors. IV. Complexing between non-mucin glycoproteins, immunoglobulins and mucins in human saliva and amniotic fluid.

By themselves the non-mucin glycoproteins of saliva and amniotic fluid produce secretory conglutinin-like factor (SKF) and secretory bacterial aggregating factor (SBAF) activity. These glycoproteins also bind immunoglobulins; a secretory binding factor for immunoglobulins (SBFI) with EDTA-reversible activity is found in amniotic fluid. Agglutination of particles by very small amounts of secretory antibody is facilitated by reversible and irreversible binding of antibody to SKF/SBAF active glycoproteins. EDTA effects on the carrier glycoproteins make the bound antibody activity EDTA-sensitive. The SKF/SBAF glycoproteins also have EDTA-sensitive interactions with each other and possibly with mucins. These complex interactions of secretory glycoproteins and immunoglobulins are of importance in mucosal protection.