Potency Differences in F VIII Concentrates Associated with Blood Groups
Differences in plasma obtained from different blood groups are well etablished. For many-years AHF Concentrate Kabi has been prepared from donations of single blood group. This fact allowed examination of the effect of blood groups on the F VIII yieldin concentrates. 211 batches of these concentrates were studied, 103 group 0, 83 group A and 25 group B. Each batch was assayed twice against a large frozen normal plasma pool (-150°C) using an automated F VIIIic assay system. Statistical analysis of the results show that there is no significant difference between A and B batches and that the A and B contain 21% on average more than the 0 batches. These results agree very well with the findings in some other studies. The implications of this are twofold: Firstly it can be seen that simply by selecting only A or B plasma for F VIII recovery a significant increase in F VIII in concentrates may be achieved. Secondly, the “normal plasma unit” and the use of normal plasma pools as reference standards heavily depend on the blood groups of the donors. This was clearly demonstrated by the chance use of a normal plasma pool containing 75 %. A group as compared to the usual use of 50 %. Quality control assays performed against this pool showed an alarming drop of 10-15% F VIII content of the production batches. Therefore F VIII potency estimation given in terms of normal plasma units are of limited value without detailed specification of the donor blood groups.