IN-VIVO RECRUITMENT OF NEUTROPHILS - CONSISTENT REQUIREMENTS FOR L-ARGININE AND VARIABLE REQUIREMENTS FOR COMPLEMENT AND ADHESION MOLECULES

The current studies examined the mechanisms of neutrophil recruitment into the rat peritoneal cavity following injection of glycogen and int o rat lungs following alveolar deposition of IgA immune complexes or a irway instillation of phorbol ester (PMA). Unexpectedly, in each model a requirement for L-arginine for neutrophil recruitment was demonstra ted, since administration of the L-arginine analogue, N-G-monomethyl L -arginine acetate (L-NMA), greatly reduced neutrophil accumulation as assessed by quantitation of neutrophils in peritoneal exudates and bro nchoalveolar lavage fluids, and by lung myeloperoxidase content. In th e case of IgA immune complex deposition, lung recruitment of neutrophi ls was also suppressed by soluble recombinant human complement recepto r-1 (sCR1) and antibody to CD18 but not by antibody to E-selectin. In contrast, neutrophil accumulation following airway instillation of PMA exhibited, surprisingly, no requirement for complement but requiremen ts for both E-selectin and CD18. These data demonstrate variable requi rements for complement, E-selectin and CD18 but a consistent requireme nt for L-arginine for neutrophil recruitment. These findings provide e vidence suggesting that L-arginine or its derivatives regulate neutrop hil recruitment.