A T cell is a type of lymphocyte, a white blood cell. T-cells plays an important role in the immune system. They attack infected cells, foreign cells, and cancer cells and completely destroy them. This stops viruses or cancer from spreading to healthy cells.
- Cytotoxic T cells (Tc cells)
- Helper T cells, (Th cells)
- Regulatory T cells (Treg cells), used to be called suppressor T cells
- Natural Killer T cells (NKT cells)
- Janeway, Charles A. et al. 2001. Immunobiology. 5th ed, New York and London: Garland. 
- The Immune System (PDF)
- (Successful!) Treatment of metastatic melanoma with autologous CD4+ T cells against NY-ESO-1