Expansion of FasL-expressing CD5+ B cells in type 1 diabetes patients

Abstract

Fas ligand drives insulitis in the non-obese diabetic mouse model of type 1 diabetes (T1D) and negatively regulates IL-10-producing (IL-10pos) CD5+ B cells in pancreata. Relevance of these phenomena to the human disease is poorly understood. 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. The majority of FasLhiCD5+ B cells did not produce cytokines and were more highly resistant to activation-induced cell death than their IL-10posCD5+ counterparts. These results associate expansion of FasL-expressing CD5+ B cells with T1D and lay the groundwork for future mechanistic studies to understand specific role in disease pathogenesis.