The Effect of Incubation Time on the Activity and Stability of Factor VIII during the Preparation Process

Hemophilia is a rare autoimmune disorder caused by autoantibodies directed in the majority of the cases against clotting factor VIII (FVIII). FVIII is extracted from human plasma or engineered from mammalian cell cultures using recombinant DNA technology. In Iran, most of the used FVIII is prepared from human plasma in Iranian Blood Transfusion Organization. It was seen important to estimate its stability and activity from bleeding time until product preparation. In the analytical study, 60 healthy male donors (20-50 years old), 15 donors from each blood group, were selected after obtaining informed consent. Donors' blood was collected in QUADRI-PACKs and centrifuged after keeping at 24°C for 2 hours. The separated plasma was divided into three groups and incubated in the lab (22°C) for 0, 90, and 180 minutes, respectively. Then, samples were stored at -20°C for one month. Afterward, the plasma was thawed, and FVIII activity was assayed. The activity of FVIII significantly (p<0.05) reduced by delay in freezing; after the time of 0 min: 134.84%±42, after 90 min: 126.88%±38, after 180 min: 120.22%±34. At all incubation times, the highest and the lowest FVIII activity were observed in A and O blood groups, respectively (p<0.05). FVIII activity was increased along with increasing age up to 35-40, but it decreased in subjects of 40-50 years old. These experiments confirmed that the longer the delay in freezing fresh frozen plasma, the greater the decrease in FVIII stability. . According to the results of this study, the best blood donors for FVIII product are those with blood group A in the age range of 40-35 years.