Antibody opsonization

Overview

Diagram illustrating antibody opsonization

Antibody opsonization is a crucial immune process where antibodies bind to the surface of a pathogen, marking it for destruction by phagocytes. This process enhances the ability of the immune system to clear infections and is a key component of the adaptive immune response.

Mechanism

Opsonization involves the binding of antibodies, such as immunoglobulin G (IgG) or immunoglobulin M (IgM), to specific antigens on the surface of a pathogen. This binding facilitates the recognition and ingestion of the pathogen by phagocytic cells such as macrophages and neutrophils.

Antibody Binding

The Fab region of the antibody binds to the antigen, while the Fc region is exposed. The Fc region can then interact with Fc receptors on the surface of phagocytes, promoting phagocytosis.

Phagocytosis

Once the antibody-coated pathogen is recognized by Fc receptors, the phagocyte engulfs the pathogen in a process called phagocytosis. The pathogen is then enclosed in a phagosome, which fuses with a lysosome to form a phagolysosome, where the pathogen is degraded by lysosomal enzymes.

Role in Immunity

Antibody opsonization is vital for the clearance of extracellular pathogens and is particularly important in the defense against bacterial infections. It also plays a role in the removal of apoptotic cells and immune complexes.

Clinical Significance

Deficiencies in opsonization can lead to increased susceptibility to infections. For example, individuals with immunodeficiencies affecting antibody production or function may experience recurrent infections due to impaired opsonization.

Related Pages

• Antibody
• Phagocytosis
• Immune system
• Adaptive immune response
• Fc receptor