RESUMO
A 61-year-old, nontransfused, Caucasian male was found to have a positive direct antiglobulin test (DAT) and an autoantibody in his serum prior to total hip replacement. Autoabsorption with the patient's ZZAP-treated red cells failed to absorb the autoantibody, giving a clue to its possible specificity, which was subsequently found to be Kell-system related. In addition, his red cells were found to have a slightly weakened expression of Kell system antigens. The patient was fit and healthy with normal hematological indices at the time of the operation. One year the hemlogical findings remained the same despite the persistence of the autoantibody and a positive DAT. This suggested that the autoantibody was benign, which was supported by a negative in vitro mactophage assay.
RESUMO
Forty-one patients with autoimmune haemolytic anaemia (AIHA), who had free antibody in their sera, were investigated for the presence of alloimmune erythrocyte antibodies using the ZZAP autoabsorption technique. Patients were subdivided into three risk categories: (I) no prior pregnancy or transfusion; (II) history of pregnancy and/or one to five transfusions; and (III) greater than 5 transfusions. A total of 13 (32%) of the 41 patients exhibited significant alloantibodies. Of 11 category-I patients 2 (18%) had significant alloantibodies. Eight (31%) of the 26 category-II patients had significant alloantibodies and 3 (75%) of the 4 category-III patients had significant alloantibodies after absorption. The majority showed Rh specificity: anti-E(8), -C(3), -Cw(1). Anti-K was found in 6 samples and 1 had anti-Fya. Alloantibodies had not been suspected prior to autoabsorption in 10 (77%) of the 13 patients with alloantibodies. These findings underline the importance of performing autoabsorption in AIHA when free autoantibody is present in the serum. Additionally, Rh phenotyping performed on ZZAP-treated cells showed complete agreement with that ascertained using pure IgM Rh typing sera and untreated cells.