T-Lymphocyte
t-lymphocyte
"A thymocyte-derived lymphocyte of immunological importance that is long-lived (months to years) and is responsible for cell-mediated immunity. T lymphocyte cells form rosettes with sheep erythrocytes and, in the presence of transforming agents (mitogens), differentiate and divide. These cells have the characteristic T3 surface marker and may be further divided into subsets according to function, such as helper, cytotoxic, etc."