Nomenclature of the Fc receptors

Fc receptors (FcR) that are specific for particular immunoglobulin isotypes are designated by Greek letters. Subtypes of receptors are denoted by capital Roman numerals, such as: Fc(γ)RI, II and III: Fc receptors for IgG on macrophages/monocytes and lymphocytes (numerals are in the order of affinity for IgG); Fc(α)=R, Fc(μ), R and Fc(δ)R : Fc receptors for IgA, IgM and IgD ; Fc(ε)RI: high-affinity receptors for IgE on mast cells and basophils; Fc(ε)RII: low-affinity receptors for IgE on lymphocytes, macrophages, and activated eosinophils. Species are abbreviated as follows: hu (human), mo (mouse), rt (rat), and rb (rabbit). Subunits of receptors are designated by Greek letters α, β, γ and transcripts by a, b, c, etc. Ig-BF describes the soluble molecules having affinity for immunoglobulin.