B lymphocytes expressing high levels of PD-L1 are key regulators of diabetes development in non-obese diabetic mice.

•Generation of transgenic mice with high PD-L1 expression on a NOD background.•NOD.PD-L1Tg mice are resistant to development of diabetes.•CD62L− CD44+ CD4+ T cells were decreased in NOD PD-L1 Tg mice.•BPD-L1 cells suppress activation of CD4+ T cells and delay onset of diabetes after adoptive transfer of diabetic T cells.