Pulmonary intravascular macrophages in the pathogenesis of bovine pulmonary lesions caused by Actinomyces pyogenes.

Rabbit antisera raised against somatic antigens from two strains of Actinomyces pyogenes reacted specifically in a peroxidase anti-peroxidase technique which was developed for the location of the bacteria in formalin-fixed tissues. The technique was applied on experimental murine and spontaneous bovine lesions caused by A. pyogenes. By electron microscopy and immunohistochemistry it was demonstrated that pulmonary intravascular macrophages play a role in the uptake of A. pyogenes from the blood, and in the production of pyaemic pulmonary lesions.