Fc region of immunoglobulin G1 (IgG1) (Fc (IgG1))

The Fc region of rituximab is the constant (crystallizable) region of the human immunoglobulin G1 (IgG1), responsible for mediating immune effector functions such as binding to Fc gamma receptors (FcγRs) on immune cells and activating complement via C1q[5][6][8]. Rituximab is a chimeric antibody with a murine variable region (Fab) for target recognition and a human Fc region for effector function. The Fc region is essential for the therapeutic action of rituximab, which works by depleting CD20-positive B cells through mechanisms dependent on Fc-mediated cytotoxicity (ADCC, CDC) and phagocytosis[3][5][7]. Structural variants of the Fc region have been engineered in antibody therapeutics to modulate pharmacokinetics, immune activation, and safety profiles[2]. The Fc region itself is not a biological receptor or therapeutic target, but its structure and glycosylation can affect the efficacy and safety of antibody drugs.

Other names

Fc fragmentIgG1 Fc regionImmunoglobulin G Fc domainFc (rituximab)Fcγ region

Engagement of Fc gamma receptors (FcγRs) on immune cells to trigger antibody-dependent cellular cytotoxicity (ADCC); Activation of complement via C1q binding to induce complement-dependent cytotoxicity (CDC); Modulation of effector functions through glycosylation or amino acid mutations.