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Transmembrane signaling pathways involved in phagocytosis and associated activation of NADPH oxidase mediated by FcyRs in human neutrophils
Author(s) -
Bianca Vittorina Della,
Grzeskowiak Miroslawa,
Dusi Stefano,
Rossi Filippo
Publication year - 1993
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.53.4.427
Subject(s) - phagocytosis , respiratory burst , biology , nadph oxidase , phospholipase d , phosphatidic acid , phospholipase c , phospholipase , diacylglycerol kinase , biochemistry , receptor , fc receptor , protein kinase c , microbiology and biotechnology , signal transduction , phospholipid , enzyme , membrane
We have previously shown that in neutrophils classical transmembrane signaling consisting of increased [Ca 2+ ]i and hydrolysis of phospholipids was not essential for phagocytosis mediated by more than one receptor (yeast‐IgG, yeast‐C3b/bi, yeast‐Con A). This work deals with the role of this transmembrane signaling in phagocytosis of erythrocyte (E) IgG, which is mediated only by receptors for IgG (FcγRs). The ingestion of E‐IgG was associated with an increase in [Ca + ]i and production of inositol phosphates, phosphatidic acid, diacylglycerol, and arachidonic acid, via activation of phospholipases G, D and A2. Related to the same number of particles ingested, the respiratory burst and the transmembrane signaling during phagocytosis of E‐IgG were much smaller than during phagocytosis of yeast‐IgG. In Ca 2+ ‐depleted neutrophils, where the increase in [Ca 2+ ]i and hydrolysis of phospholipids were lacking, the phagocytosis of E‐IgG was depressed by about 60%; the respiratory burst was also depressed due to the decrease of ingestion and of stimulation of NADPH oxidase by residual phagocytosis. Pertussis toxin (PT) did not inhibit the phagocytosis of E‐ IgG but depressed by about 40% the stimulation of li‐ pidic transmembrane signaling and the respiratory burst in normal neutrophils. In Ca 2+ ‐depleted neutrophils the toxin was without effect on ingestion and respiratory burst. Staurosporine did not inhibit the ingestion of E‐ IgG in normal and Ca 2+ ‐depleted neutrophils but depressed by 30‐40% the respiratory burst in normal and not in Ca 2+ ‐depleted neutrophils. Genistein, an inhibitor of tyrosine kinase, did not inhibit the ingestion of E‐IgG but depressed by 30‐40% the respiratory burst both in normal and Ca 2+ ‐depleted neutrophils. These results demonstrate the following findings in human neutrophils. (1) Contrary to the phagocytosis mediated by more than one receptor (yeast‐IgG, yeast‐Con A, yeast‐C3b/bi), the transmembrane signaling involving increase in [Ca 2+ ]i and hydrolysis of phospholipids plays a role in the phagocytosis and respiratory burst mediated by FcγRs alone. Thus, different signal transduction pathways can be involved in phagocytosis and associated respiratory burst depending on the receptor or combination of receptors activated. (2) FcγRs alone promote phagocytosis with two signaling pathways independent of and dependent on [Ca 2+ ]i changes and phospholipid hydrolysis and insensitive to PT, staurosporine, and genistein. (3) The signaling pathways promoting phagocytosis triggered by FcγRs alone are in some way, or at some step, different from those that activate the respiratory burst.