CD19 and type 1 diabetes mellitus: Deng et al. have described a lower frequency of CD1d expressing B cells in T1D patients, in agreement with our findings in children with T1D or C. The increased frequency of CD1d+CD27+CD19+ (mBregs) in children with a double diagnosis, compared to a single diagnosis, can be explained by the fact that checkpoint of activation and subsequent auto-antibody production [39] are partly involved in the enhanced auto-antibody secretion, thereby exacerbating autoimmune processes.