The role of Jak3 in lymphoid development, activation, and signaling.

Mutations in a number of lymphoid signaling molecules lead to immunodeficiencies in mice and humans. Among these, one very pleiotropic syndrome results from deficiencies in an array of cytokine signaling pathways utilizing a cytokine receptor common gamma chain, gammac, and the tyrosine kinase Jak3. Recent advances in our understanding of the role of gammac and Jak3 in lymphocyte development and function highlight the importance of cytokine receptor signaling pathways in regulating lymphoid homeostasis and responsiveness.