Application of the Gel Test in IgG Subclassing – A Comparison of Two Agglutination Assays

Background and objectives: IgG subclasses of anti-D seem to play some role in hemolytic disease of the newborn, but there has been disagreement as to its exact nature. The aim of our study was to evaluate a new technique for IgG subclassing of anti-D and to compare it to an established test. Materials and methods: In 31 cases of RhD immunization, we have compared two simple agglutinating assays for subclassing anti-D: an established V-well microtiter tray assay and a new gel test assay. Polyclonal rabbit anti-IgG agglutinating antibodies were tested against sensitized D-positive red blood cells by both assays. Results: The anti-D concentration in tested sera varied between 0.1 and 81 μg/ml (0.5–405 IU/ml). Both assays were simple to perform and the results correlated well. Conclusions: The gel test had two advantages: quick performance and easy interpretation.