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Streptomycin‐dependent panagglutinin causing error in forward blood grouping

Anomalous blood grouping results associated with acriflavin or tartrazine yellow dyes in anti-B reagents have been reported previously [1,2]. The present report documents, for the first time, an error in forward grouping caused by streptomycin present in monoclonal antibodies. Mr S. V., a 50-year-old patient, required blood transfusion following debridement of wounds. Preliminary grouping using whole blood on slides suggested that his group was AB, RhDpositive. However, saline-washed red cells showed his forward group as A, RhD-positive, which corroborated with his reverse serum group. Direct antiglobulin test (DAT) on his red cells was negative. No atypical antibody was detected in his serum. The patient’s whole blood was tested with a battery of anti-B from four different manufacturers. Of these, all the three monoclonal reagents showed a strong haemagglutination reaction while both the polyclonal reagents failed to do so, suggesting that the causative factor for false results was present in the monoclonal reagents. In a separate set of experiments, the patient’s saline-washed red cells, resuspended in autologous serum, were agglutinated by the monoclonal anti-B, but this reagent did not agglutinate them if they were resuspended in serum from other donors or in normal saline. Similarly, the red cells of other donors belonging to group A, resuspended in the patient’s serum, were agglutinated by monoclonal anti-B. Group O red cells resuspended in the patient’s serum were not only agglutinated by monoclonal anti-B but also by monoclonal anti-A or anti-AB (see Table 1). These observations suggest that the patient’s serum possessed a cofactor responsible for the anomalous reaction. In order to identify the incriminating factor in the monoclonal antibodies, a search was made among the different ingredients of these reagents. Ascitic fluid as antibody source, tartrazine yellow, sodium azide, thimerosal, tissue culture medium and its components were analysed individually by mixing with the red cells suspended in the patient’s serum. Interestingly, streptomycin in the tissue culture medium was found to be the factor responsible for the spurious reaction. The monoclonal anti-B dialysed to remove streptomycin was not able to agglutinate red cells suspended in the patient’s serum. Several antibiotics added to the red cell preservative solutions were responsible for false reverse grouping or antibody screening in the patients with antibodies to corresponding antibiotics [3–5]. Although streptomycin has not been previously implicated as a cause of false grouping, Martinez et al . [6] have reported on a patient in whom antibodies to streptomycin, produced through repeated intake of the drug, were a cause of immune haemolytic anaemia. In the present case, erroneous blood grouping of the patient may have been caused by antibodies to streptomycin developed as a consequence of the intake of this antibiotic during the course of his prolonged illness. However, there was no record available to indicate that he had been treated with streptomycin in the recent past. Anomalous blood grouping may be caused by a variety of artefacts, including the one described in the present report. However, such cases emphasize the need of using more than one reagent for forward ABO grouping and of reverse grouping as confirmation.