Sammenligning av metoder for eluering av IgG-antistoff bundet til erytrocytter

Background: IgG antibodies bound to erythrocytes may be involved in various disease processes. Identification of these antibodies and antigen typing of patients with a positive direct antiglobulin (DAT) test is relevant both for transfusion therapy and follow-up of patients during pregnancy. We have compared elution efficiency and concordance of results for various CE (Communauté Européenne) and IVD (In vitro Diagnostic) labelled methods and heat elution. Method: Elution methods for stripping of DAT-positive erythrocytes and for detection of antibodies in eluate were compared. McNemars test was used to compare the effectiveness of the methods. P-values < 0,05 were considered statistically significant and Holm-Bonferronis method for multiple comparisons was used. The proportion of matching results between the methods was calculated as a percentage. Results: We demonstrated significant differences in diagnostic sensitivity between the different methods. Concordance of results between methods ranged from 64 to 90 %. In antigen typing of DAT-negative erythrocytes after antibody stripping, both false negative and false positive results were observed. Conclusion: Methods for elution of IgG antibodies from erythrocytes should be included in routine investigations for certain problems. Different methods do not provide consistent results for all problems; therefore, alternative methods should be available.