A new individual variation of saliva detected with rabbit anti-human saliva serum.

A rabbit anti-saliva hyperimmune serum was raised against pooled human saliva. After absorption with human serum and semen, the immune serum formed two or three distinct precipitation lines with human saliva by the Ouchterlony method. Based on the presence or absence of a precipitation line, close to the antigen well designated as Pl, all human saliva were divided into two groups; Pl+ and Pl-. The incidence of Pl+ saliva was 114 out of 154 samples (74%). By immunoelectrophoresis with anti-saliva serum preabsorbed with Pl- saliva, Pl+ saliva formed a precipitation line in cathodal area. No amylase activity was found in this precipitation line but it was stained with the Schiff's reagent. Pl protein was isolated by Sephadex G-100 and ion-exchange chromatography. Isoelectric focusing of the Pl protein in polyacrylamide slab gel containing urea revealed that the protein differed from any known parotid salivary proteins such as Pr, Db, Pa and Pm.