An automated particle‐counting immunoassay (PACaIA) for serum IgE

Abstract

Total IgE was determined in 107 sera using a novel, automated, non‐isotopic immunoassay called PACIA (particle‐counting immunoassay) based on agglutination of anti‐IgE coated latex particles by IgE. The IgE values ranged from 10 to 50 000 iu/ml and were compared with results obtained by a conventional radioimmunoassay (RIA) which used a fast double antibody separation technique the coefficient of correlation was 0.985 and the regression line r = 0‐82 x+ 130.00. PACIA had several advantages over the RIA technique: using a sampling rate of 50.hr. results were obtained in 35 min compared to 16‐20 hr. no labelled IgE was required and the separation step, which relied on measuring the number of non‐agglutinated particles by an optical cell counter, was fully automated. The threshold of sensitivity was 10 iu/ml and the maximal coefficient of variation for between assay precision was 12‐9%.