Paul-Bunnell antigen in normal human tissues.

The BS antigen, the component of the Paul-Bunnell (P-B) antigen complex that is shared by bovine (BRBC) and sheep red blood cells (SRBC), was demonstrated in chloroform-methanol extracts from peripheral blood leukocytes of 4 of 26 healthy young individuals. One of the extracts formed a precipitation line with infectious mononucleosis (IM) sera, which merged into a reaction of identity with the corresponding line formed by the purified P-B antigen of BRBC. The BS antigen of the P-B complex was also demonstrated in tissue sediments of an apparently normal human kidney by means of mixed agglutination test with IM sera and trypsinized BRBC as the indicator. Results of this study suggest that the BS antigen is expressed in normal tissues of some individuals as an intracellular antigen, whereas in various pathologic conditions it is expressed as cell-surface antigen and/or appears in a soluble form in the patient's circulation.