Our results show that (1) Dsg3-specific B cells can be detected at low frequencies in peripheral blood of pemphigus patients, (2) Dsg3-specific memory B cells were significantly increased especially in remitting patients receiving minimal therapy, and (3) isolated Dsg3-specific memory B cells from a PV patient secreted anti-Dsg3 IgG after in vitro stimulation. The gene discussed is DSG3; the disease is acquired polycythemia vera.