The CD89 antigen (Fc alpha receptor I) binds to the Fc region of immunoglobulins alpha (IgA). CD89 mediates several immune functions including cytokine production. CD89 consists of a membrane-distal Ig-like e, Xenopus/Amphibian,tracellular domain (EC1), a membrane-pro, Xenopus/Amphibian,imal Ig-like e, Xenopus/Amphibian,tracellular domain (EC2), a transmembrane region, and a short cytoplasmic tail. This antibody recognizes the EC1 domain of human CD89 by flow cytometry and also inhibits CD89 functions.