The 13th edition of the standards of the American Association of Blood Banks specified storage at 1 to 6 degrees C for cryoprecipitated anti-hemophilic factor (Cryo) administered up to 6 hours after thawing if the Cryo is used for factor VIII (FVIII) content (Standard J4.210). Previous editions specified room-temperature (RT) storage for up to 6 hours. Currently, the temperature specification has been deleted. There are few data addressing the optimal storage temperature and maximum storage time for FVIII and fibrinogen in thawed Cryo. Thirty bags of Cryo were assayed for FVIII and fibrinogen. Each bag was divided into two aliquots; one was stored at RT and the other at 1 to 6 degrees C. Assays were performed immediately after thawing (Base) and 6 and 24 hours after thawing, respectively. All samples were filtered through 200-mu blood component infusion sets before assay. Three hundred analyses were performed, 150 each for FVIII and fibrinogen by conventional clotting technique. Data were analyzed by using a paired t test. Cryo stored at 1 to 6 degrees C for 6 and 24 hours showed an FVIII loss of 35 percent (p less than 0.0001) and 63 percent (p less than 0.0001), respectively. Cryo stored at RT for 6 and 24 hours had an FVIII loss of 8 percent (p greater than 0.05) and 20 percent (p less than 0.0001). Cryo stored at 1 to 6 degrees C for 6 and 24 hours had a fibrinogen loss of 20 percent (p less than 0.0001) and 43 percent (p less than 0.0001). Cryo stored at RT for 6 hours had no fibrinogen loss and a 2 percent loss at 24 hours (p greater than 0.05). These preliminary data show a significant loss of FVIII and fibrinogen activity in Cryo stored at 1 to 6 degrees C and filtered before assay. The FVIII and fibrinogen activity at RT is clearly maintained up to 6 hours after thawing.

A patient with acquired von Willebrand syndrome associated with polycythemia rubra Vera is described. Her plasma factor VIII procoagulant activity (67 U/dl) and factor VIII-related antigen (117 U/dl) were normal but no von Willebrand factor activity could be detected. Factor VIII crossed immunoelectrophoresis revealed decreased levels of less anodic polymeric forms of factor VIII. Mixture of her plasma or immunoglobulin G (IgG) fraction with normal plasma resulted in complete recovery of factor VIII activity and related antigen but no measurable von Willebrand factor activity, confirming the presence of an unique inhibitor. The limited specificity of this inhibitor to antigenic sites solely on the von Willebrand portion of the factor VIII bimolecular complex is distinct from all previous reports of this syndrome. This unique inhibitor offers a molecular probe to examine the von Willebrand factor: platelet interaction.

Individuals with Noonan's syndrome are likely to have one or more coagulation abnormalities: complex platelet function defects, partial Factor XI deficiency, or von Willebrand's disease. A distinctive platelet function defect has not been identified. The authors describe a 24-year-old women with Noonan's syndrome, chronic idiopathic thrombocytopenic purpura (ITP), and a platelet function defect characterized by a greater than 15-minute bleeding time, failure of aggregation and release with 10 microM ADP, 10 microM epinephrine, 750 microM arachidonic acid or 0.019 g/L collagen. A mixture of aspirin-treated platelets with the patient's platelets failed to correct the defect. Addition of 2.5 microM U46619 (a PGG2 analogue) corrected the aggregation and release defect. An electron microscopic analysis failed to reveal structural abnormalities. Thus, the platelet function defect in this patient appears to be a functional deficiency of cyclooxygenase. The presence of autoantiplatelet antibodies in a clinical setting consistent with chronic ITP raises the possibility that the defect may be acquired.