Describe the specific roles of helper, cytotoxic, and regulatory T cells in cell-mediated immunity. Which is thought to be disabled in AIDS?

Helper T cells, or CD4+ T cells, play a crucial role in the immune response by activating other immune cells, including B cells and cytotoxic T cells. They release cytokines that enhance the immune response, helping to coordinate the body's defense against pathogens. Their proper functioning is essential for a robust immune system.

Cytotoxic T cells, or CD8+ T cells, are responsible for directly killing infected or cancerous cells. They recognize specific antigens presented by infected cells and release perforins and granzymes to induce apoptosis in these target cells. This action is vital for controlling infections and eliminating tumor cells.

Regulatory T cells, or Tregs, help maintain immune tolerance and prevent autoimmune responses by suppressing the activity of other immune cells. They play a critical role in modulating the immune response to ensure it is appropriate and not overly aggressive. In the context of AIDS, the depletion of helper T cells impairs the overall immune response, including the function of regulatory T cells.