T cell types
MCAT glossary · Chemical & Physical Foundations of Biological Systems
Definition
Helper T (CD4+, MHC II binding, secretes cytokines); cytotoxic T (CD8+, MHC I binding, kills infected/tumor cells); regulatory T (suppresses response).
T cell types in plain English
T cells are specialized soldiers in your immune system, and they come in a few job types. Helper T cells (marked CD4+) are the field commanders — they don't attack directly but release signaling chemicals called cytokines that rally and coordinate the rest of the immune response. Cytotoxic T cells (marked CD8+) are the assassins — they recognize and destroy your own cells that have been hijacked by a virus or turned cancerous. Regulatory T cells are the brakes, calming the response so it stops once the threat is gone and doesn't turn on your healthy tissue. The CD4/CD8 labels are just molecular "ID badges," and MHC I and II are the display windows infected cells use to show these soldiers what's going on inside.
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