ABO blood groups, secretor status, salivary protein, and serum and salivary immunoglobulin concentrations.

Serum and salivary protein and immunoglobulin concentrations have been measured in people of different ABO blood groups and secretor status. The results have confirmed that salivary protein concentrations vary markedly according to an individual's blood group tending to be particularly high in people of group A, but have failed to show any parallel variation in serum protein concentrations. No clear differences were detected in immunoglobulin concentrations, although salivary IgA concentrations tended to be slightly higher in ABH secretors than in non-secretors.