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The customer reported false positive reactions of four donor units when tested with seraclone anti-a.The customer claimed the units yielded blood group ab test results during re-typing when they were labelled as blood group b.The blood group b of the units was confirmed by re-tests using reagents of two different manufacturers.The customer returned two vials for the supposedly defective product seraclone anti-a for investigational testing and five donor samples (one edta sample and four segments).Our quality control laboratory tested both vials of the supposedly defective product returned by the customer with different donor samples for potency and specificity.All positive and negative reactions were correct.The minimum titer of 64 was exceeded.Furthermore the donor samples (one edta sample and four segments) provided by the customer were tested with the vials of the complaint sample.All samples reacted clearly negative even after a prolonged incubation time of 60 minutes which is not according to the instruction for use.We only observed a kind of sticky effect in the immediate spin method after the centrifugation when the cell buttons had to be dislodged to observe for agglutination.But nevertheless no agglutination was observed in the donor samples provided by the customer.The reactions were clearly negative.We can only assume that the sticky effect led to a misinterpretation of the result by the customer.Testing by our quality control laboratory confirmed that the allegedly defective lot of seraclone anti-a functions correctly.A review of the batch record documentation showed no irregularities which might have negatively affected the quality of the allegedly defective lot.
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