Fatal autoimmunity results from the conditional deletion of Snai2 and Snai3

• A novel mouse strain was created with conditional hematopoietic deletion of the Snai2 and Snai3 genes (cDKO).
• The cDKO animal dies weeks after birth from acute autoimmune responses.
• The cDKO animal possesses high serum levels of autoreactive IgM and IgG.
• The autoimmunity of cDKO animal is reversed with the addition of wild type T regulatory cells.
• Loss of tolerance and generation of autoantibodies is intrinsic to cDKO bone marrow-derived cells.

Transcriptional regulation of gene expression is a key component of orchestrating proper immune cell development and function. One strategy for maintaining these transcriptional programs has been the evolution of transcription factor families with members possessing overlapping functions. Using the germ line deletion of Snai2 combined with the hematopoietic specific deletion of Snai3, we report that these factors function redundantly to preserve the development of B and T cells. Such animals display severe lymphopenia, alopecia and dermatitis as well as profound autoimmunity manifested by the production of high levels of autoantibodies as early as 3 weeks of age and die by 30 days after birth. Autoantibodies included both IgM and IgG isotypes and were reactive against cytoplasmic and membranous components. A regulatory T cell defect contributed to the autoimmune response in that adoptive transfer of wild type regulatory T cells alleviated symptoms of autoimmunity. Additionally, transplantation of Snai2/Snai3 double deficient bone marrow into Snai2 sufficient Rag2−/− recipients resulted in autoantibody generation. The results demonstrated that appropriate expression of Snai2 and Snai3 in cells of hematopoietic derivation plays an important role in development and maintenance of immune tolerance.