Memory T cells: major populations and stages of differentiation
This review is focused on commonly used flow cytometric protocols designed to identify cytotoxic T-cells and T-helpers. We review current knowledge of the various markers used to identify and characterize T cell sub-populations, especially those that indicate distinct stages of differentiation and functionality. Peripheral blood T-cells can be divided in four maim groups-na'ive cells, central memory and effector memory cells, «terminally differentiated» effector memory T-cells. With increasing differentiation, T cells change their immunophenotype and progressively acquire or lose specific functions. The main contemporary models for generating effector and memory T cell heterogeneity are also described.