Activation-induced cytidine deaminase (AID)

Definition

Activation-induced cytidine deaminase (AID) is an enzyme critical for the process of somatic hypermutation and class switch recombination in B cells. AID initiates the mutation of immunoglobulin genes, allowing for the generation of diverse antibodies during immune responses. This enzyme plays a vital role in adaptive immunity by enhancing the ability of B cells to produce high-affinity antibodies against pathogens.

5 Must Know Facts For Your Next Test

1. AID is expressed in activated B cells and is crucial for generating antibody diversity through somatic hypermutation.
2. The action of AID on DNA leads to deamination, which converts cytidine residues to uracil, creating mismatches that can result in mutations during DNA repair processes.
3. Deficiencies in AID function can lead to immunodeficiencies and a lack of effective antibody responses against infections.
4. AID also plays a role in regulating gene expression beyond immunoglobulin genes, influencing other pathways within B cells.
5. Research on AID has implications for understanding autoimmune diseases and certain types of cancer, as aberrant AID activity can contribute to genomic instability.

Review Questions

• How does AID contribute to the immune system's ability to adapt and respond to various pathogens?
  • AID contributes to the immune system's adaptability by promoting somatic hypermutation and class switch recombination in B cells. This allows B cells to generate a diverse range of antibodies with varying affinities for specific antigens. By mutating immunoglobulin genes, AID helps ensure that the body can effectively respond to a wide array of pathogens, enhancing the overall immune response.
• Discuss the potential consequences of dysfunctional AID activity in B cells and its impact on overall immune health.
  • Dysfunctional AID activity in B cells can lead to significant consequences for immune health, including immunodeficiencies and an inability to mount effective antibody responses. If AID is not functioning properly, B cells may fail to undergo somatic hypermutation or class switch recombination, resulting in a limited repertoire of antibodies. This can leave individuals more susceptible to infections and contribute to the development of autoimmune disorders or certain cancers due to aberrant genomic alterations.
• Evaluate the role of AID beyond its traditional function in antibody diversification and its relevance to cancer biology.
  • Beyond its role in antibody diversification, AID's function is increasingly recognized in cancer biology, where its activity can lead to genomic instability. AID can induce mutations not only in immunoglobulin genes but also in oncogenes and tumor suppressor genes, potentially driving tumorigenesis. This dual role highlights the importance of understanding AID's mechanisms, as dysregulation may contribute to both autoimmune diseases and cancer development, making it a critical target for therapeutic strategies.

Related terms

Somatic Hypermutation: The process by which the mutation rate of immunoglobulin genes is increased, allowing for the generation of antibodies with higher affinity for their antigens.

Class Switch Recombination: The biological mechanism that changes a B cell's production of immunoglobulin from one class to another, allowing the immune system to produce different types of antibodies.

B Lymphocytes: A type of white blood cell that plays a significant role in the immune system, particularly in the production of antibodies and memory cells.