The P blood group system in pigeon breeders and pigeon breeder's disease.

A blood group P1-like antigen has been found in gram-negative bacilli isolated from pigeon droppings, in pigeon serum, and on pigeon red blood cells. As a probable resident of the environment of the pigeon loft, the antigen stimulated formation of anti-P1 antibody in eight of 11 pigeon breeders who belonged to the P2 blood group. Only one of 11 random hospitalized patients with the P2 blood phenotype had a detectable titer of anti-P1 antibody (P less than 0.01). The titer of anti-P1 antibody was not significantly different in symptomatic vs asymptomatic breeders. The presence or absence of anti-P1 antibody could not be correlated with any band of immunoprecipitates formed between pigeon breeder's serum and crude extract of pigeon droppings. The P antigen was identified in pigeon-dropping extracts of breeders with the P2 blood phenotype by inhibition of hemagglutination. We conclude that anti-P1 antibodies appear to be a component of the immunologic response to avian antigens of pigeon breeders but are probably unrelated to the pathogenesis of pigeon breeder's disease.