Increase of interleukin‐10‐producing B cells associated with long‐term remission after i.v. immunoglobulin treatment for pemphigus

We present a refractory case of pemphigus vulgaris that achieved long‐term remission after i.v. immunoglobulin treatment (IVIG). We evaluated the fluctuation of circulating interleukin‐10‐producing B cells (B10 cells) during the course in our case and other three patients with pemphigus treated with IVIG without clinical remission. B10 cells were observed predominantly in CD1d^–, CD5^–, CD9^– and CD27⁺ populations among CD19⁺ cells in healthy controls, as well as in patients with pemphigus. The frequency of B10 cells among CD19⁺ cells increased in our case, but not in the other three patients without clinical remission, which leads to speculation on the association between the increase of B10 cells and the achievement of long‐term remission after IVIG treatment.