Keywords: BP, bullous pemphigoid; Bregs, B regulatory cells; CTLA-4, cytotoxic T-lymphocyte–associated protein 4; IRAE, immune-related adverse events; PD-1, programmed cell death protein 1; PD-L1, programmed death ligand 1; bullous pemphigoid; nivolumab; pembrolizumab; programmed cell death protein 1; programmed cell death protein 1 inhibitor.