:any of several lymphocytes (such as a helper T cell) that differentiate in the thymus, possess highly specific cell-surface antigen receptors, and include some that control the initiation or suppression of cell-mediated and humoral immunity (as by the regulation of T and B cell maturation and proliferation) and others that lyse antigen-bearing cells :t cell
- T lymphocytes differentiate in the thymus and interact directly with other cells to regulate the immune response or to kill cells expressing the appropriate antigen.
- —Alan F. Williams
- Activation of a T lymphocyte requires occupancy of its antigen-specific cell surface receptor … by its appropriate ligand (processed antigen presented by class I or class II MHC molecules) and a second signal from a growth factor.
- —Suryaprakash R. Sambhara et al.