EVALUATION OF A MODIFIED IRMA FOR ANTI-D QUANTITATION, USING H-3 PROTEIN-A

A modified immunoradiometric assay (IRMA) using tritiated (H-3) protei n A was developed to estimate anti-D concentration. The main advantage s of the assay were longer shelf life of the labelled reagent (more th an two years); minimum radiation hazard and; low non specific binding. Levels of anti-D were estimated in 23 Rh (D) immunised women. A good correlation of anti-D concentration (mug/ml) with Rh antibody titre wa s observed (r = + 0.89, P < 0.01). Anti-D concentration estimated by H -3 protein A IRMA correlated well with the severity of Rh-HDN. This as say could quantitate anti-D in sera having exclusively IgG3 subtype.