Access

Review

Nature Reviews Immunology 2, 817–830 (1 November 2002) | doi:10.1038/nri931

Lymphocide: cytokines and the control of lymphoid homeostasis

Annette R. Khaled & Scott K. Durum

In a human, about 1011 excess peripheral lymphocytes die every day. This death process maintains a constant lymphocyte population size in the face of a continuous influx of new lymphocytes and the homeostatic proliferation of old ones. Death is triggered when a lymphocyte fails to acquire signals from survival factors, the availability of which, therefore, determines the size of the pool of lymphocytes. A lymphocyte acquires survival signals through receptors for cytokines, antigens, hormones and probably other extracellular factors. Here, we discuss current concepts of the intracellular signalling pathways for survival versus death that establish cytokine-regulated lymphocyte homeostasis.