An acquired inhibitor of factor XIII with a qualitative abnormality of fibrin cross-linking.

A patient with an acquired inhibitor to factor XIII is reported. The patient's plasma produced a profound inhibition of factor XIII activity in normal plasma measured by a dansylcadaverine casein assay and stimulated a very abnormal pattern of fibrin cross-linking, not normally seen with factor XIII. Partial characterisation of the inhibitor suggests that it is heat stable and not an immunoglobulin.