Damaged membrane fragments and immune complexes in the blood of patients with Behcet's syndrome.

Electron microscopic examination of centrifuged pellets of serum from patients with Behcet's syndrome and recurrent oral ulcers revealed the presence of a large number of membrane fragments. Some of these membranes showed numerous 10 nm holes that were identical to lesions produced by the action of complement. An attempt was made to correlate complement levels, antibodies and cellular immunity with the presence of the membrane fragments, without success. However, a significant correlation was found between the membranes and the IgG class of immune complexes. The finding of membrane fragments with complement-induced damage predominantly in the blood of patients with Behcet's syndrome, and the association with soluble immune complexes suggest that the latter may generate C5b-9 complexes which may bind to the surface of cells in result in cell lysis.