Cutting Edge: Systemic Autoimmunity in Murine STAT3 Gain-of-Function Syndrome Is Characterized by Effector T Cell Expansion in the Absence of Overt Regulatory T Cell Dysfunction.

Germline gain-of-function mutations in the transcriptional factor promote early-onset multisystemic autoimmunity. To investigate how increased STAT3 promotes systemic inflammation, we generated a transgenic knock-in strain expressing a pathogenic human mutation within the endogenous murine locus. As predicted, mice develop progressive lymphoid hyperplasia and systemic inflammation, mirroring the human disease.