Cell membrane-localized antibody-antigen complex

The cell membrane-localized antibody-antigen complex is a molecular assembly formed when a monoclonal antibody binds to its specific cognate antigen on the surface of a target cell [1, 2]. This complex is the functional entity that mediates the therapeutic effects of most antibody-based drugs by serving as a scaffold for the recruitment of the host's immune system [1, 7]. Once formed, the complex can activate the classical complement pathway via C1q binding or engage Fc gamma receptors on effector cells like natural killer cells and macrophages to induce cell lysis or phagocytosis [1, 7]. Additionally, the formation of this complex often triggers the internalization of the antigen-antibody pair, a process critical for the efficacy of antibody-drug conjugates [8, 9]. In clinical practice, the density and stability of these complexes on the cell surface are key determinants of therapeutic success in treating malignancies and autoimmune disorders [2, 12]. Furthermore, the complex can directly modulate intracellular signaling pathways, leading to growth inhibition or apoptosis of the target cell [1, 2].

Other names

Membrane-bound immune complexCell surface antibody-antigen complexAntibody-antigen complex

The formation of the complex facilitates the recruitment of immune effector cells and proteins, leading to antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and antibody-dependent cellular phagocytosis (ADCP) [1, 7]. It also promotes receptor-mediated endocytosis, allowing for the internalization of the complex and any attached payloads [8, 9].