Meningococcaemia in an adult with hereditary C4b-binding protein deficiency: study of the variations of the protein S system.

Serial studies of the plasma protein C-protein S system were performed during the clinical course of a pregnant woman with meningococcaemia who recovered under therapy. The patient had limited purpura fulminans skin lesions and hereditary C4b-binding protein deficiency was suspected. This diagnosis was confirmed in the patient 1 year after delivery and also by family studies. During the meningococcaemia, an initial mild and transient acquired protein C deficiency was seen but no protein S deficiency was observed despite consumption of the latter protein. As C4b-binding protein partial deficiency is associated with high free protein S and protein S activity, this may have protected against acquired protein S deficiency during meningococcaemia.