Immune deficiencies due to defects in cytokine signaling.

Severe combined immunodeficiency (SCID) represents a syndrome comprising the most severe forms of inherited immunodeficiencies. Defects in cytokine signaling pathways can result in impaired development of lymphoid cells and/or defective functioning of these cells, and most cases of SCID result from defective signaling through the common cytokine receptor g chain (g(c)) or associated molecules and signaling pathways. Studies of these patients and the analysis of gene-targeted mice provide insight into the underlying signaling defects in inherited immunodeficiencies. The identification of the genetic defects in humans with SCID provides the basis for future therapies for these patients. More subtle deficiencies in cytokine signaling have also been found as causes of other forms of immunodeficiency, and the knowledge learned could lead to novel approaches to antimicrobial therapy.