Interleukin-17 receptor (IL-17R), also known as Interleukin-17 receptor A (IL-17RA) and CD217 antigen (CD217), is a cytokine receptor that binds interleukin 17. IL-17R/IL-17RA (CD217) is a proinflammatory cytokine secreted by activated T-lymphocytes. It is a potent inducer of the maturation of CD34-positive hematopoietic precursors into neutrophils. IL-17R/IL-17RA (CD217) is a ubiquitous type I membrane glycoprotein that binds with low affinity to interleukin 17A. Interleukin 17A and its receptor IL-17RA play a pathogenic role in many inflammatory and autoimmune diseases such as rheumatoid arthritis. Like other cytokine receptors, this receptor likely has a multimeric structure. Defects in IL-17R/IL-17RA (CD217) are the cause of familial candidiasis type 5 (CANDF5). CANDF5 is a rare disorder with altered immune responses and impaired clearance of fungal infections, selective against Candida. It is characterized by persistent and/or recurrent infections of the skin, nails, and mucous membranes caused by organisms of the genus Candida, mainly Candida albicans.