Impairment of neutrophil emigration in CD18-null mice

This study was undertaken to investigate the requirement of β2-integrins (CD11/CD18) for extravasation of neutrophils in mice. After intraperitoneal thioglycollate injection, an in vivo model of inflammation, leukocyte extravasation into the peritoneal cavity was studied in CD18-deficient and wild-type control mice. Before the induction of peritonitis, total and differential leukocyte counts in the circulation were analyzed and found to be 10-fold elevated in CD18-deficient animals compared with wild-type animals. This was largely due to neutrophilia, with a 30-fold increase in neutrophil counts. In CD18-deficient animals, extravasated white blood cells in the peritoneal cavity were diminished by 46%. The neutrophil number in the peritoneal fluid was severely reduced to 13% compared with control animals. In contrast, the number of emigrated monocytes was enhanced and lymphocyte emigration was not altered in the absence of CD18. The emigration efficiency of the neutrophils, calculated as ratio of the cell number in the lavage fluid and the circulating blood, was reduced to 0.4% in CD18-deficient mice compared with wild-type animals. Thus efficient neutrophil emigration into the peritoneal cavity strongly required CD11/CD18.

STUDIES ON THE LEUKOCYTOSIS AND LYMPHOCYTOSIS INDUCED BY BORDETELLA PERTUSSIS

Peripheral blood lymphocytes were isolated from normal mice and mice undergoing pertussis-induced lymphocytosis. After labeling in vitro with tritiated uridine the cells were transfused into normal or pertussis-treated mice. It was found that the lymphocytes from pertussis-treated mice entered the lymph nodes of both normal mice and pertussis-treated mice to a significantly lesser extent than did normal lymphocytes which had been transfused into either class of recipient. In addition, an interdependence of changes in the various body compartments examined was found when normal lymphocytes were injected into either type of recipient. However, when pertussis lymphocytes were injected into normal mice there was no interrelationship between the changes in the node with those in the blood, liver, lung, or spleen. In the case of pertussis lymphocytes transfused into pertussis-treated mice no interrelationship between any two compartments was observed. It was concluded that in pertussis-treated mice there is an inhibition of lymphocyte emigration which is primarily the consequence of an effect on the cell.