ACTIVATED HUMAN POLYMORPHONUCLEAR LEUKOCYTES REDUCE RABBIT PAPILLARY-MUSCLE FUNCTION - ROLE OF THE CD18 GLYCOPROTEIN ADHESION COMPLEX

Study objective - The aim was to determine if human polymorphonuclear leucocytes activated by human recombinant C5a(hrC5a) reduce the contractile function of the isolated papillary muscle and if this response depends upon the functional integrity of the CD18 glycoprotein adhesion complex. Design - Human neutrophils with or without pretreatment with monoclonal antibodies to the CD18 adhesion complex were added to organ baths containing isolated papillary muscles of the rabbit and activated with hrC5a. Changes in papillary muscle function were measured. Experimental material - 52 right ventricular papillary muscles isolated from rabbit and neutrophils isolated from human whole blood were used. Measurements and main results - Neither neutrophils nor hrC5a alone reduced papillary muscle function, but activation of neutrophils with hrC5a provoked reduction in myocardial contractility. This correlated with the degree of neutrophil stimulation, assessed by cell aggregation. Pretreatment of neutrophils with antibodies to the CD18 adhesion complex significantly attenuated the neutrophil induced contractile impairment. Conclusions - Activated human neutrophils can impair contractile function of papillary muscles, which is dependent upon adhesion of the leucocytes to the muscle via the CD18 complex.