Experimental leukocyte-induced pulmonary vasculitis with inquiry into mechanism.

Intravenous transfusions of washed allogeneic or autologous leukocytes in rabbits resulted in lesions of pulmonary periarteritis 48 hours later. Intact leukocytes were required. Systemic anaphylaxis, generalized Shwartzman reaction, alternate pathway complement activation and inert particle microembolism failed to produce identical lesions. Leukocytes tagged with radioactive chromium were found within arterial thromboses with proximal vasculitis. Generation or release of inflammatory factors plus thromboembolism would explain the pathogenesis of the lesions described. Specific mechanisms may be quite complex. Similar lesions have not been described in studies of pulmonary leukocyte entrapment or experimental microembolism of the lung. This model may be useful for studying pathogenetic mechanisms in pulmonary vasculitis and may have clinical implications.