Anti-Wrb, and other autoantibodies responsible for positive direct antiglobulin tests in 150 individuals

Eluates from the red blood cells (and sera whenever free autoantibody was present) of 150 individuals with positive direct antiglobulin tests, have been studied for antibody specificity. Of 87 patients with AIHA, 64 had autoantibodies reacting with all red cell samples including Rhnu11. Of these 64 anti-d1 autoantibodies, two were, and 32 contained, auto-anti-Wrb. Of 33 patients being treated with alphamethyldopa, who had developed positive direct antiglobulin tests, 23 had anti-d1 autoantibodies four of which contained auto-anti-Wrb. Of 30 haematologically normal donors with positive direct antiglobulin tests, 23 had anti-d1 autoantibodies, two of which were, and six of which contained, auto-anti-Wrb. The full specificities of autoantibodies, other than anti-Wrb and anti-d1, in the 150 patients are described, as are the natures of the protein red cell coatings that caused the positive direct antiglobulin tests. The presence of free serum autoantibody as a correlate of the three clinical conditions is reported. Several observations on auto-anti-Wrb are documented. The antibody can cause gross red cell destruction in vivo, but can be benign on other occasions; it occurs with approximately the same frequency in AIHA patients and "normal" donors with positive direct antiglobulin tests, but in fewer patients with alphamethydopa induced positive direct antiglobulin tests; it does not activate complement in vivo; and finally it may eventually provide a clue to the aetiology of AIHA.