Immune tolerance mechanisms

Definition

Immune tolerance mechanisms are processes that prevent the immune system from attacking the body's own cells and tissues, thereby maintaining homeostasis and preventing autoimmune diseases. These mechanisms are critical for distinguishing between self and non-self entities, allowing the immune system to function effectively without causing harm to the host. They play a significant role in how tumors can evade immune detection, leading to tumor progression and treatment resistance.

5 Must Know Facts For Your Next Test

1. Immune tolerance mechanisms are crucial for preventing autoimmunity, as they allow the immune system to avoid attacking the body's own cells.
2. Tumors can exploit immune tolerance mechanisms by expressing self-antigens or through the activation of immune checkpoints, which inhibit effective immune responses.
3. Regulatory T cells (Tregs) are essential for maintaining peripheral tolerance by suppressing the activity of potentially autoreactive lymphocytes.
4. Defects in immune tolerance mechanisms can lead to autoimmune diseases or enhance tumor progression by allowing cancer cells to escape immune surveillance.
5. Therapeutic strategies targeting immune tolerance mechanisms are being investigated to improve cancer immunotherapy outcomes by enhancing anti-tumor immunity.

Review Questions

• How do immune tolerance mechanisms differentiate between self and non-self entities in the context of tumor immune evasion?
  • Immune tolerance mechanisms play a vital role in differentiating self from non-self by eliminating or inactivating cells that react against self-antigens during development. In tumors, cancer cells may present self-antigens that promote tolerance instead of triggering an immune response. This allows tumors to evade detection by the immune system, as the body fails to recognize these malignant cells as threats due to their 'self' characteristics.
• Discuss the role of regulatory T cells in maintaining immune tolerance and their impact on tumor growth.
  • Regulatory T cells (Tregs) are crucial for maintaining peripheral immune tolerance by suppressing autoreactive T cells that could damage healthy tissues. In the tumor microenvironment, Tregs can be recruited and expanded, leading to enhanced immunosuppression. This suppression not only helps tumors escape immune detection but also supports tumor growth by inhibiting effective anti-tumor responses from other effector T cells.
• Evaluate how targeting immune tolerance mechanisms can enhance cancer immunotherapy strategies and improve patient outcomes.
  • Targeting immune tolerance mechanisms can significantly enhance cancer immunotherapy by reversing the suppression of anti-tumor immunity. For instance, therapies that block immune checkpoints restore the ability of T cells to recognize and attack tumor cells. Additionally, strategies aimed at depleting regulatory T cells or modulating their activity could increase the overall anti-tumor response. By overcoming these tolerance mechanisms, patients may experience better outcomes through a more robust and effective immune attack against their tumors.

Related terms

Central Tolerance:

The process by which developing T and B cells in the thymus and bone marrow are eliminated or rendered inactive if they recognize self-antigens.

Peripheral Tolerance: Mechanisms that maintain tolerance to self-antigens outside of the central lymphoid organs, including anergy, deletion, and regulatory T cells.

Immune Checkpoints: Molecular pathways that regulate immune responses, preventing excessive activation and promoting self-tolerance, often exploited by tumors to evade immune detection.