Evidence for circulating fibrin in familial Mediterranean fever.

Cryofibrinogenemia was found in 10 of 24 plasma samples (42%) from subjects with FMF. This precipitate was found during active disease as well as during intervals between crises. We found a higher incidence of cryofibrinogenemia in subjects with mild to moderately severe disease not being treated with colchicine (six of eight) as compared with colchicine-treated subjects who were in partial or complete clinical remission (four or 16; p less than 0.02). All cryofibrinogen precipitates contained fibrin, as assessed by electrophoretic analyses showing the presence of multimeric crosslinked forms of fibrin(ogen) linked by gamma-dimers. This finding in clinical specimens supports the hypothesis that fibrin in an obligatory component of cryofibrinogen. Fibrin was also found in HPF (two of six specimens) prepared from cryofibrinogen-negative FMF plasmas, thus showing that soluble forms of fibrin are even more prevalent in this disorder than is indicated by the frequent finding of cryofibrinogenemia.