Analysis of IL‐10 and IL‐35 in dipeptidyl peptidase‐4 inhibitor‐related bullous pemphigoid

Abstract The association between immunoregulatory cytokines, such as interleukin (IL)‐10 or IL‐35, and dipeptidyl peptidase‐4 inhibitor (DPP4i)‐related bullous pemphigoid (BP) has not been evaluated. Serum IL‐10 and IL‐35 levels were measured in 39 patients with BP (24 males and 15 females; 6 DPP4i‐related and 33 DPP4i‐unrelated BP patients) and 10 healthy controls. The number of CD26 + cells in the dermis around bulla on sections was counted immunohistochemically for 12 patients (six patients with DPP4i‐related BP and six randomly sampled patients with DPP4i‐unrelated BP). Patients with DPP4i‐related BP had lower levels of serum eosinophils (DPP4i‐related vs. DPP4i‐unrelated BP: 476.1 ± 234.0 vs. 911.3 ± 948.8/μL; p = 0.537) and a higher rate of infiltrating CD26 + cells (32.9 ± 7.1% vs. 15.7 ± 4.4%; p = 0.01). There were no significant differences in serum IL‐10 (6.77 ± 0.24 vs. 6.84 ± 0.20 pg/mL), serum IL‐35 (2.63 ± 0.17 vs. 2.63 ± 0.21 pg/mL), serum anti‐BP180NC16a antibodies (67.31 ± 37.4 vs. 76.18 ± 54.59 U/mL) and Bullous Pemphigoid Disease Area Index before treatment in this study. Serum IL‐10 and IL‐35 levels do not increase in patients with BP and may not be a candidate for a therapeutic target for BP. An increase in CD26 + cells might be associated with DPP4i‐related BP.