Factors related to host recognition of bacterial antigens which cause urinary infection

Some gram-negative bacteria isolated from the urinary tract have on their surfaces antigens identical to or similar to those of human blood groups A, B, or (H) O. Human isoantibodies to these antigens appear to play some part in the immunologic response to urinary infections. It is postulated from this observation that human isoantibodies A and B persist because they are important segments in resistance to infections rather than reactions to other human tissues (as in transfusions or transplantation). To further assess the relationship between bacterial antigens similar to those of blood groups A or B and host isoantibody response we performed an in-depth study of this relationship in 13 patients with urinary infection of upper or lower tracts. Isoantibody of the immunoglobulin M class appeared to be the antibody which reacted with both bacteria and human erythrocytes. Patients with infections of the upper tracts had proportionately more cross-reacting anti-B antibody than those with lower tract infections, but the amounts of anti-A antibody were roughly equivalent in both types of infection. Response of a given host was genetically predetermined. Some deficiency in host recognition of bacterial antigens was noted since only 4 of 13 patients recognized bacterial A or B antigens while all normals did so. Study of the defined crossreactions between bacterial and blood group antigens offers further opportunities for definition of the genetic components of immunity to urinary infections.