1. Check past records for known ABO groups
2. Check diagnosis for bacterial or viral infections.
3. Test the patient's red cells with AB serum. They should agglutinate due to anti-T in the AB serum.
4. To confirm T-activation, test the patient's cells with the peanut lectin Arachis hypogea (anti-T). They should agglutinate.
5. Secretor status testing may be helpful. If people are secretors, they will usually secrete their true blood group antigens.
6. To obtain the true ABO group, redo the ABO group using monoclonal typing sera that does not contain anti-T.
7. Alternatively, use ABO typing sera that has the anti-T removed (by adsorption with T-activated cells.)

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©1999 Division of Medical Laboratory Science
University of Alberta

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