Dysfunctional cytokine receptor signaling in severe combined immunodeficiency.

I have reviewed the data demonstrating that XSCID results from mutations in gamma c and that an autosomal recessive form of SCID results from mutations in Jak3, a kinase that interacts with gamma c and is responsible for transducing gamma c-dependent signals. These findings underscore the dysfunctional cytokine receptor signaling that occurs in at least two forms of SCID. Features of the biology of Jak-STAT pathways have been discussed, as have the potential roles of overactive Jak-STAT pathways in cellular transformation. Implicit in these findings are the exciting possibilities of gene therapy for XSCID and Jak3-deficient SCID, as well as the possibility that new immunosuppressive drugs might be based on the ability to disrupt Jak-STAT pathways.