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Protein kinase C and a calcium‐independent Phospholipase are required for IgG‐mediated phagocytosis by Mono‐Mac‐6 cells
Author(s) -
Karimi Kambiz,
Gemmill Trent R.,
Lennartz Michelle R.
Publication year - 1999
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.65.6.854
Subject(s) - phagocytosis , biology , phospholipase d , protein kinase c , calcium , phospholipase , phospholipase c , microbiology and biotechnology , protein kinase a , kinase , immunology , biochemistry , signal transduction , enzyme , medicine
Mono‐Mac‐6 (MM6) human monocytes ingest IgG‐opsonized particles better than other human cell lines. We compared the phagocytic signaling pathway in MM6 with human monocytes. MM6 expressed FcγRI at levels similar to monocytes, whereas FcRγII expression was approximately double. MM6 ingested IgG‐opsonized erythrocytes (EIgG) in a calcium‐independent manner. Incubation of MM6 with bromoenol lactone, an inhibitor of the phagocytic phospholipase (pPL), coordinately decreased phagocytosis and pPL activity. This inhibition was overcome by exogenous arachidonic acid, suggesting that phagocytosis requires pPL activation and arachidonic acid release. MM6 phagocytosis was inhibited with staurosporine and activated with diacylglycerol, supporting a role for protein kinase C (PKC) in this process. The pPL activators mastoparan and melittin restored phagocytosis to PKC‐inhibited cells, suggesting that pPL lies downstream from PKC. These results suggest that the MM6 signal transduction pathway for IgG‐mediated phagocytosis is similar to that of monocytes (PKCåpPLåarachidonic acidåphagocytosis). The results are discussed in the context of the finding that MM6 exhibit low phagocytosis relative to monocytes and thus may represent an attractive cell line for molecular manipulation in “recovery of function” studies. J. Leukoc. Biol. 65: 854–862; 1999.