Recombinant Human PILR-alpha Protein, CF

PILR-alpha is expressed by neutrophils, macrophages, monocytes, mast cells, APCs, microglia, neurons, cardiac muscle and renal proximal plus pancreatic duct eipthelium (4, 7, 8). It has multiple binding partners, including CD99 (4, 9), glycoprotein B/gB of HSV-1 (7), PANP (PILR-associated neural protein) (8) and NPDC1 plus collectin-12 (10). Although PILR-alpha and -beta are related through gene duplication and highly similar in their ECD aa sequence, they do not necessarily share the same ligands (or binding partners), as PILR-beta fails to bind to gB and PANP (8, 10). Notably, PILR-alpha binding appears to be dependent upon the presence of a poorly-defined peptide sequence coupled to a sialylated, O-linked carbohydrate motif (5, 9-12). It is unclear what function(s) can be attributed to PILR-alpha. One possibility suggests that in the early stage of an immune response, PILR-beta predominates over PILR-alpha on the APC surface. Ligation of PILR-beta by CD99 induces IL-12 production and immune cell activation. But this ligation also up‑regulates PILR-alpha expression, and subsequent CD99:PILR‑ alpha engagement now promotes IL-27 production, with a concomitant increase in T cell IL-10 production, and a down‑regulation of the inflammatory response (10).