ABSTRACT
A modified immunoradiometry assay (IRMA) using tritiated (3H) protein A was developed to estimate anti-D concentration. The main advantages of the assay were longer shelf life of the labelled reagent (more than 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 (micrograms/ml) with Rh antibody titre was observed (r = +0.89, P < 0.01). Anti-D concentration estimated by 3H protein A IRMA correlated well with the severity of Rh-HDN. This assay could quantitate anti-D in sera having exclusively IgG3 subtype.
Subject(s)
Enzyme-Linked Immunosorbent Assay , Female , Humans , Immunoglobulin G/blood , Immunoradiometric Assay , Isoantibodies/blood , Rh Isoimmunization , Rh-Hr Blood-Group System/immunology , Staphylococcal Protein A/diagnosis , Tritium/diagnosisABSTRACT
Using indirect immunoradiometric assay the mean (+/- SD) number of Ina antigenic sites per erythrocyte was estimated to be 73857 +/- 18285 in normal adults and 20142 +/- 8571 in newborn infants. Pregnant women showed temporary reduction in Ina antigens (28144 +/- 13857), which returned to normal levels, 3-6 months after delivery. Ina antigens were shown to be denatured by papain treatment of red cells, proving it to be of glycoprotein nature.