Plasmapheresis for severe, unremitting, chronic urticaria.

Histamine-releasing autoantibodies have been identified in chronic idiopathic urticaria. 8 patients with severe disease and histamine-releasing activity in their sera underwent plasmapheresis. Symptoms were abolished for 2 months in 1 patient and for 3 weeks in another, 2 showed almost complete resolution of symptoms, 2 had temporary relief, and the other 2 showed little change. Further investigation in 4 of the patients showed significantly reduced skin-test responses to fresh post-exchange autologous sera after plasmapheresis compared with stored pre-exchange sera, but the response to intradermal histamine remained unchanged. Blood cellular histamine increased as in-vitro serum histamine-releasing activity fell after plasmapheresis. These results favour a pathogenetic role for histamine-releasing autoantibodies in patients with chronic urticaria.