The W23-251 monoclonal antibody specifically recognizes IL-17RA (CD217), which is also known as Interleukin-17 receptor A. IL-17RA (CD217) is a ~120 kDa single-pass type I transmembrane glycoprotein that is encoded by IL17RA. IL-17RA (CD217) belongs to the IL-17 receptor family which also includes IL-17 RB, IL-17RC, IL-17RD, and IL-17RE. IL-17RA (CD217) has a wide tissue distribution and is variably expressed on granulocytes, monocytes, macrophages, dendritic cells (DCs), T cells, B cells, NK cells, smooth muscle cells, endothelial cells, and epithelial cells. Interleukin-17A (IL-17A) or IL-17F homodimers, or IL-17A:IL-17F heterodimers can bind to and signal through functional IL-17 receptor complexes comprised of IL-17RA (CD217) and IL-17RC subunits. This leads to the cellular release of proinflammatory cytokines including IL-1, IL-6, and TNF, antimicrobial peptides, and chemokines that attract neutrophils. IL-17E/IL-25 binds to and signals through another functional IL-17 receptor complex comprised of IL-17RA (CD217) and IL-17RB subunits. IL-17E/IL-25 induces type-2 (Th2-like) immune responses and is implicated in asthma. IL-17C binds to IL-17 receptor complexes comprised of IL-17RA (CD217) and IL-17RE subunits and can stimulate the production of proinflammatory cytokines and antimicrobial peptides.