CD32b / Fc gamma RIIB Antikörper

Receptors that recognize the Fc portion of IgG (Fcγ Rs) functions in the regulation of immune response and are divided into three classes designated Fcγ RI (CD64), Fcγ RII (CD32), and Fcγ RIII (CD16). Fcγ RI binds IgG with high affinity and functions during early immune responses, whereas Fcγ RII and RIII are low affinity receptors that recognize IgG as aggregates surrounding multivalent antigens during late immune responses. Three closely related genes encodes human CD32 class by and designated Fcγ RII A, B, and C which share 94 - 99% amino acid identity in their extracellular domains. Fcγ RII B (CD32b) is expressed on cells of both myeloid and lymphoid lineages as well as on cells of non-hematopoietic origin. As the only inhibitory member in human, Fcγ RII B has an intrinsic cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM) and delivers an inhibitory signal upon ligand binding. The coordinated functioning of activating and inhibitory receptors is necessary for successful and proper initiation, amplification, and termination of immune responses, and accordingly, the Fcγ RII B plays an important negative-regulating role through modulating the signals from activation receptors. Recent study has identified CD32b expression in a variety of B-cell malignancies, suggesting that it is a potential immunotherapeutic target for B-cell lymphoproliferative disorders.

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