Adherence of neutrophils to canine cardiac myocytes in vitro is dependent on intercellular adhesion molecule-1

The adhesiveness of isolated canine cardiac myocytes for neutrophils is greatly increased by stimulation with cytokines such as tumor necrosis factor α (TNFα). Since this adhesion is significantly inhibited by an anti-CD 18 MAb, experiments were performed to test the hypothesis that the newly expressed adhesion molecule on the cardiac myocytes was intercellular adhesion molecule-1 (ICAM-1). A newly developed MAb, CL18/6, was found to exhibit the functional and binding characteristics with canine neutrophils and canine jugular vein endothelial cells expected of an antibody recognizing ICAM-1. MAb CL18/6 also bound to isolated cardiac myocytes after stimulation of the myocytes with cytokines, and it blocked by > 90% the adhesion of neutrophils to stimulated myocytes. A partial cDNA clone for canine ICAM-1 was isolated, and ICAM-1 mRN A was found to be increased in both endothelial cells and cardiac myocytes after cytokine stimulation. Cytokines that both increased the CL18/6-inhibitable adhesion of neutrophils to myocytes and induced expression of ICAM-1 were IL-1β, TNFα, and LPS. These results are consistent with the conclusion that canine endothelial cells and cardiac myocytes express ICAM-1 in response to cytokine stimulation, and that ICAM-1 functions as an adhesive molecule for neutrophils on both cell types.