LILRA2
Description
The LILRA2 (leukocyte immunoglobulin like receptor A2) is a protein-coding gene located on chromosome 19.
Leukocyte immunoglobulin-like receptor subfamily A member 2 (LILRA2, CD85H, ILT1) is a protein that in humans is encoded by the LILRA2 gene. Leukocyte Ig-like receptors (LIRs) are a family of immunoreceptors expressed predominantly on monocytes and B cells and at lower levels on dendritic cells and natural killer (NK) cells. All LIRs in subfamily B have an inhibitory function. LIRs in subfamily A, with short cytoplasmic domains lacking an immunoreceptor tyrosine-based inhibitory motif (ITIM) and with transmembrane regions containing a charged arginine residue, may initiate stimulatory cascades. One member of subfamily A (LILRA3) lacks a transmembrane region and is presumed to be a soluble receptor. LILRA2 senses microbially cleaved immunoglobulin to activate human myeloid cells.
LILRA2 plays a role in the innate immune response against microbial infections by recognizing N-terminally truncated immunoglobulins produced by bacterial and fungal pathogens, including Legionella pneumophila, Mycoplasma hyorhinis, Streptococcus pneumoniae, Staphylococcus aureus, and Candida albicans. It binds to specific epitopes on these cleaved immunoglobulins, including portions of the variable region of immunoglobulin light chains, but also requires the constant region for signaling. LILRA2 recognizes cleaved IgM, IgG3, and IgG4 but not cleaved IgA1. Binding of these cleaved immunoglobulins activates neutrophils, monocytes, and eosinophils. In monocytes, activation leads to the release of CSF2, CF3, IL6, CXCL8, and CCL3 and down-regulates responses to bacterial lipopolysaccharide (LPS), potentially through the down-regulation of TLR4 expression and reduced signaling via TLR4. In eosinophils, activation results in the release of RNASE2, IL4, and leukotriene C4. LILRA2 does not bind class I MHC antigens.
LILRA2 is also known as CD85H, ILT1, LIR-7, LIR7.
