CD89 Rabbit Recombinant mAb detects endogenous levels of total CD89

CD89 (FcαRI) is the human myeloid IgA Fc receptor expressed on cells, such as neutrophils, eosinophils and monocytes/macrophages. It is a transmembrane glycoprotein that binds both subclasses of IgA in all its molecular forms (i.e. monomeric, dimeric and secretory IgA) via a region of its membrane-distal EC1 domain. Various cytokines and other factors can modulate surface expression of CD89. CD89 is up-regulated on neutrophils in response to formyl-methionyl-leucyl-phenylalanine (FMLP), interleukin 8 (IL-8), and tumor necrosis factor α (TNF-α). The CD89 levels can also be modulated by Ca2+-dependent signaling processes in both neutrophils and eosinophils. The expression of CD89 on monocytes and monocyte-like cell lines can be up-regulated by Calcitriol, lipopolysaccharide (LPS), TNF-α, granulocyte-macrophage colony stimulating factor (GM-CSF) and IL-1β, and downregulated by suramin and transforming growth factor-β (TGF-β). CD89 appears to play an important role in immune defense by linking the humoral IgA response to powerful cellular effector mechanisms.