Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)

Definition

Antibody-dependent cell-mediated cytotoxicity (ADCC) is an immune response mechanism in which antibodies bound to target cells stimulate the destruction of those cells by effector cells, such as natural killer (NK) cells. This process involves the recognition of antibody-coated target cells and the subsequent release of cytotoxic granules by the effector cells, leading to the lysis and elimination of the target cells.

5 Must Know Facts For Your Next Test

1. ADCC is an important mechanism of the adaptive immune system, allowing antibodies to recruit and activate effector cells to eliminate target cells.
2. The process of ADCC involves the binding of antibodies to specific antigens on the surface of target cells, which then triggers the activation of effector cells, such as natural killer (NK) cells.
3. Activated effector cells release cytotoxic granules containing substances like perforin and granzymes, which induce apoptosis (programmed cell death) in the target cells.
4. ADCC plays a crucial role in the immune system's defense against viral infections, as well as in the elimination of cancer cells and the clearance of antibody-coated pathogens.
5. The efficiency of ADCC can be influenced by factors such as the type and affinity of the antibody, the expression of Fc receptors on effector cells, and the activation state of the effector cells.

Review Questions

• Describe the mechanism of antibody-dependent cell-mediated cytotoxicity (ADCC) and its role in the immune response.
  • Antibody-dependent cell-mediated cytotoxicity (ADCC) is a process in which antibodies bound to target cells, such as virus-infected or cancer cells, trigger the activation of effector cells, like natural killer (NK) cells. The antibodies act as a bridge, binding to the target cells and engaging the Fc receptors on the effector cells. This interaction activates the effector cells, causing them to release cytotoxic granules containing substances like perforin and granzymes. These substances then induce apoptosis, or programmed cell death, in the target cells, effectively eliminating them from the body. ADCC is an important mechanism in the adaptive immune response, allowing the immune system to efficiently target and destroy specific cells that pose a threat.
• Explain the role of natural killer (NK) cells in the ADCC process and how their activation contributes to the overall immune response.
  • Natural killer (NK) cells play a crucial role in the ADCC process. These effector cells express Fc receptors on their surface, which can bind to the Fc portion of antibodies that are attached to target cells. This binding activates the NK cells, triggering the release of cytotoxic granules containing perforin and granzymes. The perforin creates pores in the target cell membrane, allowing the granzymes to enter and induce apoptosis. The activation of NK cells through the ADCC mechanism enhances the immune system's ability to recognize and eliminate specific target cells, such as virus-infected or cancer cells. By recruiting and activating these powerful effector cells, ADCC significantly contributes to the overall adaptive immune response against various threats to the body.
• Analyze the factors that can influence the efficiency of antibody-dependent cell-mediated cytotoxicity (ADCC) and discuss how these factors may impact the immune system's ability to effectively eliminate target cells.
  • The efficiency of antibody-dependent cell-mediated cytotoxicity (ADCC) can be influenced by several factors. The type and affinity of the antibody involved in the process is crucial, as different antibody isotypes and their binding strength to the target cell can affect the degree of effector cell activation. The expression and distribution of Fc receptors on the surface of effector cells, such as natural killer (NK) cells, also plays a key role in determining the effectiveness of ADCC. Additionally, the activation state of the effector cells, which can be influenced by various cytokines and other immune signals, can impact their ability to release cytotoxic granules and induce apoptosis in the target cells. Factors that modulate these aspects of the ADCC process can have a significant impact on the immune system's capacity to effectively eliminate virus-infected, cancerous, or antibody-coated cells. Understanding and manipulating these factors may be crucial in developing therapeutic strategies that harness the power of ADCC to enhance the body's defense against various diseases.

Related terms

Antibody: A protein produced by B cells that binds to specific antigens, marking them for destruction by the immune system.

Natural Killer (NK) Cells:

A type of lymphocyte that can directly kill infected or cancerous cells without the need for prior sensitization.

Cytotoxicity:

The ability of a substance or cell to kill or damage other cells, often used in the context of the immune system's ability to destroy target cells.