Pulmonary intravascular macrophages in rabbits experimentally infected with rabbit haemorrhagic disease.

Attention has already been drawn to the presence of pulmonary intravascular macrophages (PIMs) in species in which the lung plays an important part in the removal of particles from the bloodstream. The stimulation of PIMs under certain conditions has been related to pulmonary oedema and congestion. In order to ascertain whether these cells are found in rabbits, healthy animals were inoculated with a liver homogenate obtained from animals which had died of rabbit haemorrhagic disease, a condition characterized by vascular phenomena and pulmonary oedema. PIMs were detected both in experimental and healthy control animals. They shared the morphological characteristics reported for other species, particularly with respect to the presence of intercellular junctions with endothelial cells. In experimental animals, PIMs were actively involved in the removal of cell debris which may or may not have been associated with the presence of rabbit haemorrhagic disease virus antigen.