Effect of adhesiveness of white blood cells on pulmonary vascular permeability and resistance

We studied pulmonary vascular injury evoked by mechanically activated white blood cells (WBCs). In isolated perfused rat lungs, changes in pulmonary vascular resistance were measured, and a gravimetric method was used to measure the pulmonary vascular filtration coefficient, which was taken as an index of pulmonary vascular injury. WBCs were activated by gentle agitationin a glass container for 10 sec. The filtration coefficient was measured tinder baseline conditions, and then inactive or activated WBCs were added to the perfusate. The perfusion was stopped for 90 minutes and then the lungs were reperfused. The expression of CD18 on the surface of WBCs was measured by flow cytometry. The filtration coefficient and the pulmonary vascular resistance in lungs exposed to activated WBCs were about 2.5 times and 3.3 times higher, respectively, than those in the lungs exposed to inactive WBCs. These results indicate increases in resistance and in pulmonary vascular permeability. The results of flow cytometry indicated that the mechanical agitation increased the expression of CD18 on the surface of WBCs. In conclusion, WBCs in which adhesiveness has been increased can induce pulmonary vascular injury and can increase pulmonary vascular resistance.