This project proposes to study the reaction of polymorphonuclear leukocytes (PMNL) and serum to bacterial infection and other causes of inflammation. We shall investigate the cellular biology of these PMNL, the nature of the modulator of PMNL motility, which we have identified in the serum of patients with bacterial infection, and the interaction of the two. Phagocytosis, bactericidal activity, properties of cellular adherence, and cell surface charge will be compared in PMNL with enhanced directional and random motility, those with decreased random and directional motility, and those with normal motility. Levels of cyclic nucleotides (cAMP and cGMP), cellular ATP, and magnesium-ATPase activity will also be compared. NADH and NADHP oxidase activities will be measured using a fluorometric assay procedure developed in our laboratory. We shall attempt to isolate and purify the factor we have identified in the serum of patients with bacterial infection, which modulates PMNL motility. Standard analytical and preparative techniques (e.g. chromatography, polyacrylamide gel electrophoresis) will be used. The effects of the factor upon PMNL physiology (phagocytosis, bactericidal activity, cell adherence properties) and biochemistry (oxidative metabolism, concentrations of cyclic nucleotides, cellular ATP and magnesium-ATPase activity) will be determined. We shall employ the "ecto-enzyme" magnesium-ATPase which we identified in our laboratories in an effort to highly purify human PMNL membrane. Finally, we shall develop a model using the synthetic tripeptide N-formyl met-leu-phe which simulates the effects upon PMNL and serum that we have observed during bacterial infection. This will be done using the tripeptide in vitro and by administering various doese of this substance in vivo to guinea pigs, and thereafter studying the cellular biology of their circulating PMNL.