Thanks for your response! I agree that this seems like a logical "check" of treatment and we tried this with Anti-M and the cells were still weakly positive. I don’t believe that the antigens are always destroyed, but are “altered.” We did not feel like this was a good test of treatment as it could be very subjective and not as clear cut as N negative becomes macroscopically positive. While the literature I read does state that the M and N antigens are denatured, this was not a suggested method of checking the enzyme treatment. The published method is to test treated N negative cells with N lectin. Since the publication tell us to use N lectin, we were hoping to find another source of N lectin so that we would not have to complete a huge validation on another method that is not as reliable.