Immunologic Tolerance Mechanisms

Antigens and Immune Tolerance

• Autoantigens, alloantigens, and xenogeneic antigens are types of antigens that need to be tolerated by the immune system.
• Autoantigens are the body's own proteins, alloantigens are from the same species but genetically different, and xenogeneic antigens are from different species.

Functions of Normal Gut Bacteria

• Normal gut bacteria, also known as the gut microbiome, have several functions including:
  • Helping with digestion and nutrient absorption
  • Producing vitamins and hormones
  • Maintaining the integrity of the gut epithelial lining
  • Modulating the immune system
• The normal function NOT performed by gut bacteria is initiation of an immune response.

Mechanisms of Tolerance to Commensal Bacteria

• One mechanism that maintains tolerance to commensal bacteria in the gut is the induction of regulatory T cells.
• These T cells downregulate the immune response to prevent excessive inflammation and maintain homeostasis in the gut.

Test your knowledge on immunologic tolerance mechanisms in relation to commensal microbes and paternally derived antigens. Explore the concepts of coexistence and immune system tolerance in this informative quiz.