Selective plasma exchange can reduce auto-antibodies in patients with bullous pemphigoid without affecting factor...

Bullous pemphigoid (BP) is an autoimmune blistering skin disorder characterized by circulating serum IgG antibodies against two hemidesmosomal proteins: BP180 and BP230. Fundamentally, immunosuppressive therapies are administered to treat this disease, but plasmapheresis can be added for refractory patients. We experienced the case of a 63-year-old patient with refractory BP for which we administered double filtration plasmapheresis (DFPP). His skin lesions improved along with decreased IgG BP180 antibodies, but factor XIII (FXIII) and fibrinogen were also reduced by DFPP repetition. Reportedly, deficiency of those factors can cause lethal bleeding. Especially, decreased FXIII cannot be detected by prolongation of bleeding or coagulation time. To prevent further reduction of those factors and bleeding complications, DFPP was switched to selective plasma exchange (SePE), a new modality of plasmapheresis that uses a membrane plasma separator with smaller than ordinary pores. SePE further reduced pathogenic IgG BP180 antibodies, but FXIII and fibrinogen recovered. For this case, we measured the mean of reduction ratios in serum IgG and FXIII both before and after plasmapheresis sessions and detected the decreased levels of FXIII and fibrinogen during DFPP. We were able to switch to SePE from DFPP appropriately before any bleeding event occurred. The utility of SePE was demonstrated, especially for the reduction of pathogenic antibodies with retention of FXIII and fibrinogen, which have the longest half-lives among coagulation factors and which take a long time to recover.