CD5 and type 1 diabetes mellitus: Here, using splenocytes from T1D, autoantibody (Ab+), and non-diabetic (ND) human subjects, we show that a subpopulation of CD5+ B cells that is characterized by expression of FasL (FasLhiCD5+) was significantly elevated in T1D subjects, many of whom had significantly reduced frequency of IL-10posCD5+ B cells compared to Ab+ subjects.