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.