Interleukin-2

Definition

Interleukin-2 (IL-2) is a cytokine that plays a critical role in the immune system, primarily in the activation and proliferation of T cells. It is produced mainly by activated CD4+ T helper cells and is essential for the growth and differentiation of T cells, which are crucial for adaptive immunity. IL-2 also influences other immune cells, such as B cells and natural killer cells, linking it to various immune responses, including those involved in transplantation and immune tolerance.

5 Must Know Facts For Your Next Test

1. Interleukin-2 is crucial for the proliferation of T cells after they have been activated by an antigen, helping them multiply and mount an effective immune response.
2. It can be used therapeutically in cancer treatments to enhance the body’s immune response against tumors by promoting the growth of T cells.
3. High levels of IL-2 can lead to a stronger immune response, but can also contribute to autoimmune disorders if not regulated properly.
4. In the context of transplantation, IL-2 plays a dual role; it can promote immune rejection of transplanted tissues if not adequately controlled.
5. Regulatory T cells (Tregs) produce IL-2 to help maintain immune tolerance and prevent excessive immune responses against self-antigens.

Review Questions

• How does interleukin-2 contribute to the activation and proliferation of T cells within the immune system?
  • Interleukin-2 is essential for the activation and proliferation of T cells as it acts as a growth factor. Once CD4+ T helper cells recognize an antigen, they produce IL-2, which binds to receptors on nearby T cells. This interaction triggers a signaling cascade that promotes cell division and differentiation into effector T cells, enhancing the overall immune response.
• Discuss the implications of interleukin-2 in the context of transplantation and how it affects transplant acceptance or rejection.
  • Interleukin-2 plays a critical role in transplantation by influencing whether a transplant is accepted or rejected. Elevated levels of IL-2 can activate T cells that recognize foreign antigens from the transplanted organ, leading to rejection. Conversely, controlling IL-2 production through immunosuppressive therapies can promote tolerance and acceptance of the transplant, highlighting its dual role in both enhancing immune responses and contributing to transplant complications.
• Evaluate how dysregulation of interleukin-2 levels can lead to autoimmune diseases or impact cancer therapy outcomes.
  • Dysregulation of interleukin-2 levels can significantly impact immune homeostasis. Excessive IL-2 production may lead to an overactive immune response, resulting in autoimmune diseases where the body attacks its own tissues. On the other hand, insufficient IL-2 activity during cancer therapy may prevent adequate activation of T cells needed to target tumors effectively. Balancing IL-2 levels is thus crucial for maintaining effective immunity while preventing detrimental autoimmune reactions.

Related terms

Cytokines:

Signaling proteins that mediate and regulate immunity, inflammation, and hematopoiesis, acting as communication molecules between cells.

T Cells: A type of white blood cell that plays a central role in cell-mediated immunity, recognizing and responding to specific antigens.

Immune Tolerance:

The process by which the immune system does not attack certain antigens, such as those from transplanted organs or tissues, preventing rejection.