[Detection of drug-induced antibodies to erythrocytes in the gel test]. / Nachweis medikamentenabhängiger Antikörper gegen Erythrozyten im Geltest.

Drug-induced immune hemolytic anemia is a serious hematological disorder which results from increased red blood cell destruction due to the production of autoantibodies, drug (metabolite)-dependent antibodies (DDAb) or both types of antibodies, even in one patient by the same drug. One of the major problems related to DDAb is that the causative drug (metabolite) usually does not bind tightly to target cells, and the antibodies are completely removed from the cells by conventional washing procedures, i.e. by the antiglobulin test. We have recently shown that the microtube geltest, by which the antiglobulin test is performed without washing the cells, is a highly sensitive and reliable alternative method for the detection of all kinds of DDAb. The results obtained with different DDAb are discussed.

Red blood cell transfusion in warm-type autoimmune haemolytic anaemia.

Blood transfusions are regarded as hazardous in patients with warm-type autoimmune haemolytic anaemia (AIHA) because of potential intensification of haemolysis and a presumed high incidence of alloimmunisation. We have retrospectively analysed data of 79 multitransfused patients (74 adults, 5 children) with detectable warm autoantibodies and transitory or persisting haemolytic anaemia. All patients had received blood transfusions on at least two occasions. Patients were reexamined at least twice within the first 6 months of transfusion (duration of follow-up 6 months-12 years). 53 patients had received blood transfusions because of decompensated AIHA, all of whom presented with detectable autoantibodies against red blood cells. None of these patients had transfusion-related alloimmunisation or a definite increase in haemolysis, even when the transfused red cells were serologically incompatible because of free serum autoantibodies. The other 26 patients had no signs of AIHA at presentation (negative direct and indirect antiglobulin test), but received blood transfusions for anaemia due to various other causes. 23 of these 26 patients went on to develop alloantibodies as well as autoantibodies upon transfusion, and 3 patients developed autoantibodies alone. Our findings do not support the generally accepted notion that transfusion therapy should be avoided in AIHA patients. Rather, they indicate that the incidence of alloimmunisation as well as adverse haemolytic transfusion reactions are less common in AIHA patients than in other multitransfused patients.

Detection of cell-drug (hapten)-antibody complexes by the gel test.

Most drugs causing immunocytopenias do not bind firmly to the affected cells. Consequently, the drug-dependent antibodies in such cases are completely removed from their binding sites by conventional cell washing. It has recently been shown that such cell-drug-antibody complexes do survive the washing procedure, if the drug (metabolite) was included in the wash medium. The study reported here used the microtube gel test to reexamine the reactivity of different drug-dependent red cell antibodies: cefotaxime (n = 1), carbimazole (n = 1), cianidanol (n = 1), diclofenac (n = 3), penicillin (n = 3), and nomifensine (n = 10). Whether the drug tested binds (penicillin, cianidanol, carbimazole, and diclofenac) or does not bind (cefotaxime and nomifensine) firmly to the cells, the resultant cell-drug-antibody complex could be recognized on and/or in the gel after it was separated from the mixture containing the drug by means of centrifugation alone and without washing. It is concluded that the gel test might be of value not only for the detection of drug-dependent antibodies, but also for the analysis of subtle drug--cell interactions.