STUDY ON THE SUPEROXIDE-PRODUCING ENZYME OF EOSINOPHILS AND NEUTROPHILS - COMPARISON OF THE NADPH OXIDASE COMPONENTS

It has been known that eosinophils produce more superoxide anion (O-2( -)) than neutrophils. To elucidate the mechanism involved in the diffe rence in the superoxide-producing activities, we compared the NADPH ox idase components and the translocation of the cytosolic components bet ween eosinophils and neutrophils. Membrane-bound cytochrome b(558), cy tosolic p47-phox, p67-phox, and p40-phox were present in both neutroph ils and eosinophils, but the amounts of these components were 1.5- to 3.3-fold greater in eosinophils than neutrophils. Upon activation, p47 -phox, p67-pbox, and p40-phox were translocated to the membranes in bo th leukocytes, but larger amounts were translocated in eosinophils tha n in neutrophils. Furthermore, the cross-mixing experiments using memb rane and cytosol of eosinophils and neutrophils revealed that more cyt osolic components were translocated, and more superoxide-producing act ivities were obtained using eosinophil fractions. Interestingly, K-m v alues of activated oxidase for NADPH were almost the same in any combi nation of membrane and cytosol from both leukocytes, indicating that o xidase components are likely similar in both eosinophils and neutrophi ls. These observations suggest that NADPH oxidase components are more abundant in eosinophils than neutrophils, and, upon activation, larger amounts of NADPH oxidase complex are formed in eosinophils than in ne utrophils. (C) 1997 Academic Press.