First, let's discuss what is meant by the phrase, “US Standard of Potency”. The FDA has very strict guidelines that all manufacturers must meet when preparing blood grouping reagents. Whether the reagents are monoclonal or polyclonal, the FDA outlines exactly what is expected of reagents. In the FDA Docket 845-0181, the FDA outlines potency titer values (strength of reaction at a stated dilution), specificity results (including specific cells to test), and other details of testing that must be performed on each lot of antisera, such as Anti-A or Anti-B, that a manufacturer prepares for the US market. This docket covers ABO and Rh Blood Grouping Reagents, as well as Rare Blood Grouping Reagents. For reagents prepared under these guidelines, the package insert will state “Meets FDA potency requirements.”
“No U.S. Standard of Potency” is found on the package insert for Quotient Anti-A1, as a bullet on the top left section of the insert. Quotient Anti-A1 is a lectin, and there is no US Standard of Potency for lectins. In the Code of Federal Regulations, there is a US Standard of Potency for Anti-A1, but it only applies if the Anti-A1 is prepared from human plasma or human-derived monoclonal antibodies. For lectins, there is no potency standard. Although the statement may be found in a different location of the insert, if you look closely, you will see that the package inserts for all Anti-A1 lectins sold in the US have this statement.
“No U.S. Standard of Potency” will also be found on the package inserts of Reagent Red Cells. Perhaps the future will hold a time when manufacturers are able to grow red cells, but for now, reagent red cells are prepared using blood from humans. Molecular studies are reinforcing what many have always suspected: no two human beings are alike. So there is no FDA Standard of Potency for reagent red cells. This does not mean that the FDA has no guidelines or requirements. Section 21 CFR 660, Subpart D outlines donor suitability, collection of blood, testing of the source material, processing guidelines and labeling. There are also requirements that dictate the samples and paperwork that manufacturers must submit to the FDA with each lot of final product.
“No U.S. Standard of Potency” certainly does not mean that there is no US standard of quality!