IFN-γ

Definition

IFN-γ, or interferon-gamma, is a cytokine that plays a crucial role in the immune system's response to pathogens and the regulation of the inflammatory process. As a key signaling molecule, IFN-γ coordinates various immune cells and functions to mount an effective defense against infections and promote tissue repair.

5 Must Know Facts For Your Next Test

1. IFN-γ is primarily produced by T cells and natural killer (NK) cells in response to the presence of pathogens or other immune stimuli.
2. IFN-γ enhances the ability of macrophages to kill intracellular pathogens, such as bacteria and viruses, by increasing their phagocytic and microbicidal activities.
3. IFN-γ promotes the differentiation of T helper cells towards the Th1 phenotype, which is essential for the clearance of intracellular pathogens.
4. IFN-γ can inhibit the proliferation of certain viruses and induce the expression of major histocompatibility complex (MHC) class I and II molecules, enhancing antigen presentation to T cells.
5. Dysregulation of IFN-γ production or signaling has been implicated in the pathogenesis of various autoimmune and inflammatory disorders.

Review Questions

• Explain the role of IFN-γ in the activation and function of macrophages during an immune response.
  • IFN-γ plays a crucial role in enhancing the microbicidal and phagocytic activities of macrophages, which are essential for the clearance of intracellular pathogens. When macrophages encounter pathogens, they release IFN-γ, which then binds to receptors on the macrophage surface. This binding triggers a signaling cascade that increases the expression of genes involved in pathogen recognition, phagocytosis, and the production of antimicrobial molecules, such as reactive oxygen and nitrogen species. As a result, macrophages become more effective at killing and degrading intracellular pathogens, thereby contributing to the overall immune response.
• Describe how IFN-γ influences the differentiation of T helper cells and the implications for the immune response.
  • IFN-γ is a key cytokine that promotes the differentiation of naive T helper cells towards the Th1 phenotype. Th1 cells are essential for the clearance of intracellular pathogens, as they secrete additional IFN-γ and other cytokines that activate macrophages, cytotoxic T cells, and natural killer cells. By driving Th1 cell differentiation, IFN-γ helps to establish a cell-mediated immune response that is tailored to effectively combat intracellular infections. This process is critical for the coordination and regulation of the overall immune response, as the Th1-dominated response initiated by IFN-γ helps to eliminate the threat of intracellular pathogens.
• Analyze the potential implications of dysregulated IFN-γ production or signaling in the context of immune-mediated diseases.
  • Aberrant production or signaling of IFN-γ has been implicated in the pathogenesis of various autoimmune and inflammatory disorders. For example, excessive or prolonged IFN-γ signaling can lead to the inappropriate activation of immune cells, resulting in chronic inflammation and tissue damage, as seen in conditions like rheumatoid arthritis, multiple sclerosis, and inflammatory bowel disease. Conversely, impaired IFN-γ production or signaling can compromise the immune system's ability to effectively clear infections, potentially leading to increased susceptibility to pathogens. Understanding the delicate balance of IFN-γ regulation is crucial for developing targeted therapies to restore immune homeostasis and mitigate the effects of IFN-γ dysregulation in immune-mediated diseases.

Related terms

Cytokine: Cytokines are small proteins secreted by various cells, including immune cells, that act as signaling molecules to regulate immune responses and inflammatory processes.

T cells: T cells are a type of lymphocyte that play a central role in cell-mediated immunity, recognizing and responding to specific antigens presented by other cells.

Natural Killer (NK) cells: Natural killer cells are a type of cytotoxic lymphocyte that can directly kill infected or cancerous cells without prior sensitization.