1. Check the past records in case the patient is a known group A.

2. Check the diagnosis for bacterial infection (with or without Ca of the colon or rectum).

3. If using human polyclonal reagents, redo the ABO group using monoclonal anti-A and anti-B typing sera, which may resolve the problem.

4. If using monoclonal reagents, redo the ABO group using human polyclonal anti-A and anti-B typing sera.

5. If using a monoclonal reagent containing ES4 anti-B, neutralize the the anti-B portion that reacts with galactosamine by adding 0.1 M galactosamine to the anti-B, before doing the ABO group. (As QC, show that reactions with normal group B cells are not inhibited.)

6. Try secretor status studies (usually not necessary). If the patient is group A and a secretor, he will secrete A and H antigens only. (As QC, set up known secretor and non-secretor salivas).

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©1999 Division of Medical Laboratory Science
University of Alberta

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