Even though the percentage of IL-10 producing PCs was increased in the Breg population, the fraction of total PCs that produced IL-10 was significantly decreased in active disease, consistent with the conclusion that the onset of autoimmunity in MRL/lpr mice was associated with an expansion of PCs but a decrease in differentiation toward the Breg phenotype in this population. This evidence concerns the gene IL10 and Autoimmunity.