RESUMO
In an immunohematology reference laboratory, samples received for antibody identification react in many different ways requiring a variety of approaches. Sometimes, the clues from initial testing can lead to faulty assumptions and misdirection. Fortunately, a well-supplied reference laboratory will have access to a variety of techniques and reagents that, when used together, can reveal the true identity of the antibodies involved. We present a case of a patient sample with an apparent group AB, D+ blood type showing strong reactivity with all cells tested in the forward and reverse ABO, in the D testing as well as in a three-cell antibody screen. The initial assumption was that the plasma contained a cold autoantibody. Subsequent testing, including the use of gel column technology, ficin-treated cells, and antisera for phenotyping, showed the apparent cold autoantibody to bea red herring. Additional tube testing at immediate spin, 37°C,and indirect antiglobulin test (IAT) revealed the presence of four alloantibodies: anti-M and anti-E reacting at immediate spin, 37°C, and IAT plus anti-Fy(a) and anti-Jk(b) reacting at lAT.