Factor V antibody and disseminated intravascular coagulation.

A factor V inhibitor arose in a 79-year-old man within 1 month of an operation for a fractured leg. Absorption studies with solid-phase antibodies to human immunoglobulins showed the inhibitory activity to be primarily in the IgG class, but also in the IgA class, of immunoglobulins. This is the first report of an IgA immunoglobulin with factor V inhibitory activity. While the inhibitor was present, and at a time when no circulating Factor V activity was detectable, the patient developed septicemia and disseminated intravascular coagulation. The mechanism sustaining disseminated intravascular coagulation despite the absence of circulation factor V activity remains unexplained. The factor V inhibitor disappeared within 5 months of its initial detection. Possible origins of factor V inhibitors are discussed.