The nature of secretory agglutinins and aggregating factors. II. Biochemical and immunochemical properties of factors in human saliva and amniotic fluid.

Secretory conglutinin-like factor (SKF) and secretory bacterial aggregating factors (SBAF) of saliva and amniotic fluid were characterized as high molecular weight non-mucin glycoproteins. Most biochemical tests or procedures used in previous investigations did not permit an unequivocal distinction among immunoglobulins, non-mucin glycoprotein, or mucin factors. Partitioning with hot phenol enabled the separation of a high molecular weight non-mucin glycoprotein fraction from saliva and amniotic fluid with SKF and SBAF activity that was distinct from mucins and antibodies. Non-mucin glycoproteins, immunoglobulins and mucins represent three classes of secreted molecules capable of clumping bacteria.