[Plasmapheresis in light urticaria. A rational therapy concept in cases with a proven serum factor].

Plasmapheresis represents a new and powerful treatment for solar urticaria and has been performed in a couple of patients so far. Since therapeutic responses have been observed exclusively in cases exhibiting a pathogenetically important serum factor, plasmapheresis seems to work specifically by elimination of this photoallergen. It is easy to demonstrate a serum factor by in vitro irradiation of the patient's serum and subsequent autologous reinjection into the skin, inducing the generation of wheals. In contrast to transfer tests, this method does not bear the risk of HIV infection. In view of the extreme difficulty in administering conventional therapy for solar urticaria, the present encouraging results suggest that plasmapheresis should be considered in patients who show a serum factor.