Thus, our findings of decreased peanut-specific IgE and IgG1, but preserved total IgE and IgG1, increased frequencies of CD4+ IL-4+ T cells, and blunted peanut-induced anaphylaxis in UTX-TCD mice compared to littermate controls mirrored these previously reported results, suggesting a possible defect in the regulatory T cell and Tfr compartments of UTX-TCD mice. This evidence concerns the gene IGHE and anaphylaxis.