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IgM‐mediated opsonization and cytotoxicity in the shark
Author(s) -
McKinney E. C.,
Flajnik Martin F.
Publication year - 1997
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.61.2.141
Subject(s) - antibody opsonization , cytotoxicity , biology , phagocytosis , antibody , macrophage , antibody dependent cell mediated cytotoxicity , effector , population , cytotoxic t cell , microbiology and biotechnology , immunology , opsonin , biochemistry , monoclonal antibody , in vitro , demography , sociology
Two types of cytotoxic reactions have been observed using cells from the nurse shark: spontaneous cytotoxicity mediated by cells of the macrophage lineage and antibody‐dependent killing carried out by a different effector cell population. Previous data showed that removal of phagocytic cells using iron particles abolished macrophage‐mediated killing, but not antibody‐dependent reactions. The current study used single cell assays and showed that the effector of antibody‐driven reactions was the neutrophil. Surprisingly, the mechanism of killing was shown to be phagocytosis mediated by both 7S and 19S immunoglobulin M (IgM). Reactions proceeded with as little as 0.01 μg of purified 19S or 7S IgM and were complete within 4–6 h. In contrast, purified immunoglobulin did not adsorb to macrophages and had no effect on target cell binding or cytotoxicity. Pretreatment of cells with cytochalasin D abolished the phagocytic reaction, but not spontaneous cytotoxicity. These data show that antibody‐mediated killing results from opsonization and phagocytosis; the mechanism of macrophage killing is currently unknown. In addition, these data show that the shark neutrophil, not the macrophage lineage, carries a receptor for Fcμ. J. Leukoc. Biol . 61: 141–146; 1997.