Figure 6-19
Other receptors present on leukocytes exploit ITAMs for signal transduction
• FcγRIII (CD16) – a receptor for the Fc end of IgG that triggers antibody dependant cell-mediated cytotoxicity (ADCC) by NK cells. This receptor is also present on macrophages and neutrophils where it allows binding and endocytosis of antibody bound pathogens. The ITAMs reside on a ζ chain, such as those present in the TCR complex, or a γ chain, a relative of the ζ chain, either of which would be associated with the FcγRIII receptor.
• γ chains are also associated with FcεR1 receptors on mast cells. Cross-linking of these leads to degranulation of the mast cells
• Dap10 and Dap12, also members of the ζ chain family. Dap12 contains a single ITAM while Dap10 recruits PI 3-kinase. They work together in NK cells to signal the release of cytotoxic granules by which NK cells kill their targets.
• Certain viruses, such as Epstein-Barr virus, have acquired ITAMs which enables them to trigger B-cell proliferation by similar mechanisms that B-cells use to proliferate upon antigenic stimulation.