The 6C4 monoclonal antibody specifically recognizes two isoforms of human CD32, Fc gamma RIIA and Fc gamma RIIB. From alternative mRNA splicing, 6 isoforms of CD32 have been reported. CD32 is a 40 kDA polymorphic transmembrane glycoprotein expressed on monocytes, macrophages, graulocytes, B cells, and platelets. The receptor has low affinity toward IgG and is involved in immunomodulation, phagocytosis, and the inflammation response. The 6C4 antibody in a rosette blocking assay is reported to inhibit Ig binding