Normally-occurring precipitating antibodies against Staphylococcus aureus in human serum and colostrum.

Crossed immunoelectrophoresis was used to study precipitating antibodies against Staphylococcus aureus in sera from 263 normal persons and in 10 colostrum samples. A polyspecific protein-A free S. aureus antigen preparation and a corresponding rabbit antiserum constituted the reference system. All the sera contained precipitins against 6-10 S. aureus antigens. One of these was teichoic acid, and the titre of antibodies against cell wall teichoic acid varied from person to person, in contrast to other commonly occurring antibodies. The precipitin score, which expresses the number and titre of precipitins in each serum, increased with age. Colostrum contained 3 precipitins, which were not present in the corresponding maternal sera.