ABO, phosphoglucomutase and erythrocyte acid phosphatase typing of blood samples containing added fluoride

Blood samples containing approximately 2% and 4% sodium fluoride have been stored at 4 degrees C for up to 5 months and 4 weeks respectively. ABO typing by absorption-elution was successful on stains made from almost all of the samples. PGM subtyping by isoelectric focusing was successful on most samples, with clearer results from whole blood than from stains. Failure to type appears to be slightly more common at the higher preservative level and yields no result rather than an erroneous one. Apparent phenotypic changes in the 1+ and 1- bands have been seen after 5 months storage. EAP typing by isoelectric focusing was successful on most samples, again with clearer results from whole bloods than from stains. Possible errors can occur in samples containing C bands, but it is not clear whether they are caused by the presence of preservative. The results obtained are illustrated by two casework examples.