Antibody-dependent cell-mediated cytotoxicity (ADCC)

Definition

Antibody-dependent cell-mediated cytotoxicity (ADCC) is an immune response mechanism where antibodies bind to target cells, marking them for destruction by immune cells such as natural killer (NK) cells. This process plays a vital role in the elimination of infected or cancerous cells, showcasing how the immune system can harness the specificity of antibodies to direct innate immune cells to perform targeted attacks. ADCC is crucial in maintaining immune surveillance and can be disrupted in various immune disorders.

5 Must Know Facts For Your Next Test

1. ADCC relies on the interaction between Fc receptors on NK cells and the Fc region of antibodies bound to target cells, leading to the activation of NK cell cytotoxicity.
2. The effectiveness of ADCC can vary based on the affinity and isotype of the antibody involved, with IgG being the most efficient at mediating this process.
3. ADCC is especially important in controlling viral infections and tumor surveillance, highlighting its role in the immune system's ability to target abnormal cells.
4. Disruptions in ADCC can lead to increased susceptibility to infections and cancer, as the body may fail to adequately eliminate harmful cells.
5. Therapeutic monoclonal antibodies are designed to enhance ADCC, providing targeted treatment options for certain cancers and autoimmune diseases.

Review Questions

• How does the mechanism of antibody-dependent cell-mediated cytotoxicity (ADCC) contribute to the immune response against infections?
  • ADCC contributes to the immune response by utilizing antibodies that tag infected or abnormal cells for destruction. When an antibody binds to its target, it exposes its Fc region, which can then interact with Fc receptors on NK cells. This interaction triggers NK cell activation and leads to the release of cytotoxic granules that induce apoptosis in the targeted cells. Thus, ADCC enhances the ability of the immune system to clear infections effectively.
• Discuss the impact of monoclonal antibodies on enhancing antibody-dependent cell-mediated cytotoxicity (ADCC) in cancer treatment.
  • Monoclonal antibodies are engineered to specifically target cancer cell antigens, promoting ADCC by binding to these cells and facilitating their recognition by NK cells. By enhancing the immune response through this mechanism, monoclonal antibodies increase the likelihood of eliminating cancerous cells. This therapeutic strategy has been successful in treating various malignancies by effectively harnessing ADCC to improve patient outcomes.
• Evaluate how disruptions in antibody-dependent cell-mediated cytotoxicity (ADCC) can affect overall immune function and lead to disease states.
  • Disruptions in ADCC can lead to compromised immune function, making individuals more vulnerable to persistent infections and cancers. For instance, if NK cells cannot effectively recognize or eliminate antibody-tagged targets due to deficiencies in Fc receptor expression or function, it could result in uncontrolled viral replication or tumor growth. This impairment underscores the importance of ADCC in maintaining immune surveillance and preventing disease, illustrating how deficiencies in this process can contribute to significant health issues.

Related terms

Natural Killer (NK) Cells: A type of lymphocyte that plays a major role in the host rejection of tumors and virally infected cells, capable of recognizing and killing cells without prior sensitization.

Monoclonal Antibodies: Laboratory-made antibodies that are identical and can bind to specific antigens, often used in therapies to enhance ADCC against target cells.

Cytotoxic T Lymphocytes (CTLs): A subtype of T cells that directly kill infected or cancerous cells; while similar to ADCC, CTLs use a different mechanism to recognize and destroy their targets.