Antibody fragment crystallizable region (Fc region)

The Fc region is the tail portion of an immunoglobulin (antibody) molecule required for recruiting effector functions of the immune system. When an antibody is bound to a target cell (e.g., via its Fab region), the Fc region remains exposed and can interact with Fc receptors (FcRs) on immune cells such as macrophages, natural killer cells, and dendritic cells, as well as proteins of the complement system. These interactions trigger processes such as phagocytosis, ADCC, and complement-mediated lysis, crucial for the destruction of antibody-coated pathogens or tumor cells. The structure and glycosylation patterns of the Fc region influence its binding to different Fc receptors and thereby modulate the intensity and type of immune response. Many therapeutic antibodies are engineered to optimize Fc region interactions for enhanced efficacy or reduced toxicity.

Other names

Fragment crystallizable regionFc fragmentFc domain

Fc receptor engagement leading to ADCC and phagocytosis Complement activation (antibody-dependent complement deposition) Modulation of immune cell activity (via Fcγ, Fcε, Fcα receptors)