Antibody response to Arcanobacterium haemolyticum infection in humans.

Arcanobacterium haemolyticum causes pharyngitis, exanthema, and other infections. The evidence of the pathogenicity of A. haemolyticum depends on clinical descriptions of culture-positive patients and a comparison of carrier rates of patients with pharyngitis and healthy, matched controls. In this investigation, the antibody response of the host was studied for the first time, using SDS-PAGE and Western blot analyses. Paired acute and convalescent sera showed development of antibodies to A. haemolyticum in 7 of 8 patients. The antibodies reacted primarily with four distinct cell wall-associated proteins with estimated molecular masses of 80, 60, 50, and 30 kDa. Moreover, the reactivity of convalescent sera from 19 patients was compared with that of sera from 19 controls. Antibodies to A. haemolyticum were found in sera from 16 patients and 6 controls (P < .005); the antibody response of the patients was strong compared with that of the controls. These results indicate that A. haemolyticum infection induces an antibody response in the host.