Subpopulations of lymphocytes: a review

Human lymphocytes comprise a heterologous population of cells which can be sub-divided on functional criteria or on the basis of surface membrane markers. Although it is widely accepted that human lymphocytes are broadly divisible into thymus dependent (T) and thymus independent (B) cells, recent evidence suggests that at least in humans this distinction may not be as clear cut as previously thought. An assessment of the relative numbers of T and B cells in human peripheral blood and lymphoid tissues can be made utilizing these marker systems. This has led to a reclassification of human lymphoid diseases according to the T and B cell concept, which might be of value in characterising the immunological status in health and disease, and may allow a more rational approach to the therapy of immune deficiency states and lymphoid malignancies.