What problems are shown in the ABO group and what do they suggest?

The ABO shows two problems:

  • A weak reaction in the front cell group with anti-A, including mixed-field agglutination microscopically.

    In most adults reactions in the front group are 3+ or 4+. Weak reactions suggest a possible weak subgroup of A, for example, A3 or weaker. Mixed-field is associated with the A3 subgroup, a multitude of other causes, as well as with transfusion. In the case of transfusion, two red cell populations are present, one with the corresponding antigen and one without.

  • The 1+ reaction in the reverse group with A1 cells.

    In adults without impaired humoral immunity (e.g., those without a- or hypogammaglobulinemia), anti-A and anti-B in the reverse group typically reacts 3+ or 4+. (Note: If a person is missing one ABO antibody due to weak or missing immune globulins they must be missing both anti-A and anti-B since they are both composed of immune globulins.) Unexpected antibodies such as anti-A1 and other cold-reactive antibodies (anti-Lea, -M, -N, -P1, and autoanti-I) may react w+ to 4+ depending on their strength.

In this case the presence of a weak reaction with anti-A in the front group (including mixed-field agglutination) combined with the extra 1+ reaction with A1 cells suggests multiple possible resolutions and must be investigated further.