ALBUMIN EXCHANGE AND INFLAMMATORY CELL RECRUITMENT IN LUNGS OF ANTIGEN-CHALLENGED GUINEA PIGS : ROLE OF HISTAMINE

Microvascular albumin exchange and sequestration of inflammatory cells into the lungs of anesthetized guinea pigs immunized to ovalbumin were evaluated using radioactive tracers. Increased exchange of radiolabeled (*) albumin from airways to blood was noted in immunized and boosted animals under basal conditions. After the intratracheal injection of 300 micrograms of ovalbumin, an additional increase in exchange through epithelium occurred, since the rate of appearance of *albumin in blood was enhanced compared with control (140 +/- 30 vs. 54 +/- 20% in 1 h). The augmentation of lung content in extravascular *albumin compared with control (16.2 +/- 4.0 vs. 5.9 +/- 1.6%) indicates that transendothelial exchange was also facilitated. Concomitment with the sequestration of *platelets into the lungs of antigen-challenged sensitized animals (59.2 +/- 20% in 1 h), leukocytes (> 60% polymorphonuclear neutrophils) did not marginate. Histamine released during antigenic shock might promote leukocyte demargination f...