Automatic red cell washing machine for quantitative assay of anti-D concentration

Anti-D immunoglobulin preparations: the stability of anti-D concentrations and the error of the assay of anti-D

An analysis of the assay of 28 preparations of anti-D immunoglobulin using a radioisotope method carried out at 6-montly intervals for 2--4.5 years showed an average fall in anti-D concentration of 10.6% each year, with 99% confidence limits of 6.8--14.7%. The fall in anti-D concentration after storage at 37 degrees C for 1 month was less than 8%, the minimum change that could be detected. No significant change in physical characteristics of the immunoglobulin were detected. The error of a single estimate of anti-D by the radioisotope method (125I-labelled anti-IgG) used here was calculated to be such that the true value probably (p = 0.95) lay between 66 and 150% of the estimated value.

Radioelectroimmunoassay of anti-D immunoglobulin on agarose plates containing whole red cells

By incorporating whole Rh(+) red cells in an agarose plate and adding a small amount of purified 125I anti-D immunoglobulin as a tracer to standards and samples, a radioelectroimmunoassay (REIA) of anti-D immunoglobulin was possible. The results by this method agree with those obtained by the direct method. The coefficient of variation (within plate precision) is less than 9% and the reproducibility is 12% (coefficient of variation for a plasma sample assayed on six occasions during 1 month). The International anti-D serum was compared with the WHO standard preparation 68/419 on five occasions and found to contain 11; 11; 10; 9 and 11 mug per ampoule.