suppressor T cells
Summary
Suppressor T cells, now usually called regulatory T cells (Tregs), are T cells that turn down the activity of other T and B cells after a threat is cleared and help prevent attack on self. Testable point: they dampen the immune response, unlike helper T cells (amplify) and cytotoxic T cells (kill).
Detail
Meaning: Suppressor T cells downregulate the adaptive immune response. By restraining helper T cells, cytotoxic T cells and B cells, they help end the response once the antigen is gone and maintain tolerance to self-antigens, which limits autoimmunity. Many textbooks list them alongside helper, cytotoxic and memory T cells. Modern immunology usually calls them regulatory T cells (Tregs), typically CD4⁺ cells marked by the transcription factor FOXP3, while some older texts describe them as CD8⁺. They act partly by releasing inhibitory cytokines such as IL-10 and TGF-β.
On the MCAT: Passages ask you to predict what happens when this population is lost or overactive. Too little suppression suggests a prolonged or excessive response, autoimmunity or allergy-like reactions. Too much suppression suggests a weaker response to infection or tumor cells. Questions also ask you to match each T cell type to its role: helper cells activate, cytotoxic cells kill infected cells, suppressor cells shut the response down, and memory cells persist for faster secondary responses.
Common confusion: Students read "suppressor" as suppressing the pathogen, but these cells suppress the immune system's own cells. Cytotoxic T cells are the ones that kill infected cells. Also, HIV depletes helper T cells (CD4⁺ effector cells), so loss of suppressor function is not what causes AIDS.
Sources
- Campbell Biology
- Janeway's Immunobiology
Written for the MCAT and checked before it was published. For study reference only. Spotted an error? Let us know.