Inhibitory receptor involved in the down-regulation of the immune response (PubMed:10026201, PubMed:24935931). Receptor for FN1 (PubMed:34089617). Receptor for integrin ITGAV/ITGB3 (PubMed:11323698). Inhibits IgE-mediated mast cell activation, at least in part through interaction with ITGAV/ITGB3 (PubMed:8855262, PubMed:10026201, PubMed:11457897, PubMed:11323698). Also inhibits KITLG/SCF-mediated mast cell activation (PubMed:12884301). Through interaction with ITGAV/ITGB3, inhibits antibody production by memory and marginal zone B cells, probably by suppressing their differentiation into plasma cells (PubMed:24935931). Inhibits IFNG production by CD8 T cells, CD4 T cells and natural killer cells (PubMed:12682239). Inhibits antigen presentation by dendritic cells to T cells, preventing T cell activation (PubMed:18792399). Inhibits lipopolysaccharide-mediated neutrophil-dependent vascular injury (PubMed:14557414). Suppresses the allergic inflammatory response by inhibiting infiltration of neutrophils and eosinophils and preventing mast cell degranulation (PubMed:17761953). Inhibits lysis by natural killer cells (PubMed:8977169). Interacts (when tyrosine phosphorylated) with SH2 domain-containing phosphatases PTPN6/SHP-1 and PTPN11/SHP-2; interaction with PTPN6 enhances inhibition of mast cell activation. Expressed on mast cells and natural killer cells (at protein level) (PubMed:8977169, PubMed:8977170, PubMed:11457897). Expressed on neutrophils (at protein level) (PubMed:14557414). Expressed on eosinophils (at protein level) (PubMed:17761953). Expressed on dendritic cells (at protein level) (PubMed:18792399). Expressed on memory and marginal zone B cells (at protein level) (PubMed:24935931). Expressed on CD8 T cells (at protein level) (PubMed:12682239). Expressed in the uterus of pregnant mice where it is detected at day 4.0 of pregnancy with levels dropping at day 4.5 (PubMed:9338594). Highly expressed in the luminal epithelium of uterine endometrium with lower levels in the glandular epithelium (PubMed:9338594). Induced by lipopolysaccharide on neutrophils (at protein level) (PubMed:14557414). Induced by IL6 and LIF (PubMed:9338594). Contains 2 copies of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases. Tyrosine phosphorylated. No effect on fertility or litter size (PubMed:10982834, PubMed:11457897). Normal development of mast cells and natural killer cells (PubMed:10982834). Increased severity of local and systemic anaphylactic reactions (PubMed:11457897). Significantly increased sensitivity to IgE-dependent passive cutaneous anaphylaxis with greater tissue swelling and mast cell degranulation, and significantly greater and faster death rate in active systemic anaphylaxis (PubMed:11457897). However, another study found no effect on mast cell activity with no increase in mast cell degranulation (PubMed:10982834). Macroscopic hemorrhages following intradermal injection of E.coli lipopolysaccharide with increased neutrophil numbers around the site of injection (PubMed:14557414). Normal B cell development and memory B cell formation but increased production by marginal zone and memory B cells of IgM after a primary immunization and of IgM, IgG1 and IgE after a secondary immunization (PubMed:24935931). Reduced ERK activation and reduced Prdm1/Blimp1 expression, indicative of suppression of plasma cell differentiation (PubMed:24935931). No effect on antigen uptake or cytokine production by dendritic cells but dendritic cells show enhanced antigen presentation to T cells and induce increased T cell stimulation (PubMed:18792399). Increased neutrophilia, eosinophilia and mast cell degranulation following ocular ragweed (RW) sensitization and challenge, and increased lung inflammation following RW sensitization and challenge (PubMed:17761953). Increased Kitlg/SCF-induced mast cell degranulation and tissue swelling (PubMed:12884301). Enhanced IFNG production by CD8 T cells, CD4 T cells and NK cells following viral infection (PubMed:12682239).