PENTOXIFYLLINE AND CD14 ANTIBODY ADDITIVELY INHIBIT PRIMING OF POLYMORPHONUCLEAR LEUKOCYTES FOR ENHANCED RELEASE OF SUPEROXIDE BY LIPOPOLYSACCHARIDE - POSSIBLE MECHANISM OF THESE ACTIONS

Lipopolysaccharide (LPS) primes human polymorphonuclear leukocytes (PMN) for enhanced O-2(-) production in response to stimulation by N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe). Serum factor is essential for priming at lower concentrations of LPS. Complexes of LPS and LPS-binding protein are recognized by CD14 on PMN. We investigated the effects of a monoclonal antibody against CD14 (MY4) and of pentoxifylline (POF) a membrane fluidizer, alone and in combination, on LPS-LPS-binding protein enhancement of PMN superoxide production. LPS plus serum potentiated the fMet-Leu-Phe-induced activation of phospholipase D evidenced by increased phosphatidic acid formation. Phosphatidic acid formation and O-2(-) production were inhibited by MY4 and POF. Our results suggest that the actions of these agents occur at an early step in the excitation-response sequence. In the absence of a second stimulus, LPS plus serum caused an increase in the amount of G(i) alpha(2) associated with the membrane via CD14 POP, however, had no effect on G(i) alpha(2) in the membrane. POF alone significantly changed the affinity (K-D) of the fMet-leu-Phe receptor of PMN (from 25.2 +/- 4.5 nM to 15.2 +/- 2.4 nM [P < 0.01; 11 = 4]) at 37 degrees C. The differences between the sites of action of MY4 and POF may lead to cooperation by these agents for inhibition of priming by LPS plus serum for enhanced O-2(-) production. Clinical use of the antibody and POF may diminish tissue damagecaused by PMN in clinical endotoxic shack.