Identification of transcalciferin as a major component of human parotid saliva by crossed immunoelectrophoretic mapping.
Human parotid saliva collected from Stenson's duct during sour candy-stimulated salivation was studied by crossed immunoelectrophoresis (X-IEP). Eleven antigens were identified in a pool of salivas from 10 adult, caucasoid males and females. Four were related to serum antigens, three being previously known: IgG, IgA and albumin. The fourth was identified as Gc globulin, also known by function as transcalciferin. Salivary Gc is electrophoretically different from serum Gc, migrating as an alpha 2-beta component rather than as an alpha 1 globulin. The quantities of 8 of the 11 antigens detected by X-IEP were compared for salivas from 10 subjects. These quantities and their ratios to each other were highly variable, indicating idiosyncratic secretory patterns. Only quantities of amylase were moderately consistent from donor to donor. Quantitatively, Gc is a major antigen in parotid saliva. Large proportions of a salivary antigen, alpha 1c, were found in two of the 10 subjects--adult males who never had developed caries. Among the other 8 subjects, all with caries, proportions of alpha 1c were much lower, and 2 subjects lacked it. None of the other antigens measured showed any correlation with caries resistance. The nature and function of alpha 1c are unknown.