Which cells bear CD4 and CD25 markers?
a.) Regulatory T cells b.) Th2 cells c.) Cytotoxic T cells d.) Th1 cells
The correct answer and explanation is:
The correct answer is a) Regulatory T cells.
Regulatory T cells (Tregs) are a specialized subset of T cells that play a critical role in maintaining immune tolerance and preventing autoimmune diseases. These cells bear both CD4 and CD25 markers on their surface.
- CD4 is a co-receptor molecule expressed on helper T cells, including Tregs, and plays a vital role in recognizing antigens presented by MHC class II molecules on antigen-presenting cells (APCs). The presence of CD4 allows these cells to interact effectively with APCs during immune responses.
- CD25 is the alpha chain of the interleukin-2 (IL-2) receptor, which is essential for the survival and function of Tregs. IL-2 is a cytokine that stimulates T cell proliferation, and CD25+ Tregs use IL-2 in a way that helps them regulate immune responses by suppressing the activation of other immune cells.
Regulatory T cells are involved in maintaining immune homeostasis by suppressing excessive immune responses that could lead to inflammation or autoimmunity. They are crucial in preventing the immune system from attacking self-tissues and in limiting the severity of immune responses to foreign pathogens.
In contrast:
- Th2 cells (option b) also express CD4, but they do not typically bear CD25.
- Cytotoxic T cells (option c) do not express either CD4 or CD25; they are primarily characterized by their expression of CD8.
- Th1 cells (option d) also express CD4, but like Th2 cells, they do not typically express CD25.
Thus, CD4 and CD25 are markers that are most strongly associated with regulatory T cells, which are essential for immune regulation and tolerance.