IMMUNE CELL-MIGRATION THROUGH THE ARTERIAL-WALL IN THE MURINE LUNG DURING A PULMONARY INFLAMMATORY RESPONSE

Perivascular accumulation of leukocytes in the lung was induced by int ratracheal administration of sheep erythrocyte antigen to primed mice. The route of migration of intravascular leukocytes to the perivascula r space in the lung, in particular from arteries, and the structure of lymphatic vessels among the aggregated leukocytes were examined by tr ansmission electron microscopy. Leukocytes-lymphocytes, granulocytes, monocytes and macrophages-were demonstrated to adhere to the endotheli al surface and to migrate between endothelial cells to reach the inter nal elastic lamina of arteries. Becoming conspicuously constricted, th e leukocytes penetrate through this elastic lamina. They further migra te through the smooth muscle layer to the interstitium, passing throug h the external elastic laminar region. At 2 days after antigen adminis tration, dilated lymphatic vessels containing large numbers of leukocy tes in the lumen and bearing endothelial gaps open to the interstitium began to be seen. The lymphatic walls were more convoluted and richer in pinocytotic vesicles than those prior to antigen challenge. This s tudy confirms the light microscopic findings by CURTIS et al. (1990) t hat arteries, besides veins, venules and capillaries, may represent a major route of inflamatory cell entry into the lung parenchyme in an a cute and vigorous immune response. In addition, lymphatic vessels were suggested to be newly formed for the transport of fluid and immune ce lls from the sites of inflammation in the lung.