Natural and engineered disorders of lymphocyte development.

Mammals have evolved complex developmental pathways to generate a large repertoire of B and T lymphocytes capable of mounting effective immune responses. Analysis of natural and engineered immunodeficiencies constitutes a powerful approach to delineating these pathways and identifying the molecular sensors that couple the survival of developing lymphocytes to the achievement of successful gene rearrangements at the loci coding for B and T cell antigen receptors. Besides identifying cytokines, growth factors, and transcription factors involved in lymphocyte development, genetic analysis also makes it possible to organize most of these protagonists into gene networks that control critical events in the life of developing lymphocytes.