Premium
Immunoglobulin G‐mediated phagocytosis activates a calcium‐independent, phosphatidylethanolamine‐specific phospholipase
Author(s) -
Lennartz Michelle R.,
Lefkowith James B.,
Bromley Frances A.,
Brown Eric J.
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.54.5.389
Subject(s) - phagocytosis , biology , phospholipase d , phosphatidylethanolamine , opsonin , phospholipase a , phospholipase a2 , in vitro , phospholipase , phospholipase c , biochemistry , receptor , calcium , microbiology and biotechnology , enzyme , phospholipid , chemistry , phosphatidylcholine , organic chemistry , membrane
Inhibition of arachidonate release down‐ regulates immunoglobulin G‐mediated phagocytosis. This arachidonate requirement is selective for IgG‐ opsonized targets, suggesting that arachidonate may act as a second messenger for Fcγ receptor‐mediated phagocytosis. Here we report the characterization of a phospholipase, activated during phagocytosis, that releases arachidonate from phosphatidylethanolamine in the absence of intracellular calcium ([Ca] i ≤ 2 nM). In vitro, a phospholipase with these characteristics was detected in soluble and particulate fractions of human monocyte homogenates. ( E )‐6‐(Bromomethylene)tetrahydro‐3‐(l‐ naphthalenyl)‐2H‐pyran‐2‐one, a drug that selectively inhibits Ca‐independent phospholipase A 2 S, is shown to inhibit IgG‐mediated phagocytosis and its associated arachidonate release in intact monocytes as well as the in vitro enzyme activity. These findings provide a link between the whole‐cell and in vitro data and present the initial characterization of a receptor‐activated, calcium‐ independent phospholipase from human monocytes.