Human IgE antibody serology: A primer for the practicing North American allergist/immunologist

Indoor and food allergen-specific IgE levels are presented in kU_A/L as measured by 3 FDA-cleared autoanalyzers in the C-2008 and A-2009 cycles of the Diagnostic Allergy SE Survey conducted by the College of American Pathologists. Each specimen was twice diluted ∼2.75-fold from the previous dilution. All 3 methods displayed good interlaboratory within-assay agreement and linearity with interdilution coefficient of variation <15%. However, differences in the absolute levels of IgE antibody measured among the 3 assays are shown, with desired intermethod coefficients of variation <20% observed in only ∼20% of the measurements performed. Two different sera were analyzed for IgE antidog, and they show clear IgE heterogeneity-related intermethod differences. The same serum specimen was analyzed by participating laboratories in 2 separate survey cycles for IgE antipeanut, and these confirmed intermethod differences. Reproduced with permission from Hamilton RG. Proficiency survey based evaluation of clinical total and allergen-specific IgE assay performance.

IgE specific activity (allergen-specific IgE to total IgE ratio) for 20,238 total IgE:allergen-specific IgE pairs involving 182 allergen specificities. A, The ordinate at a linear variable. B, The same data as the common log of the IgE specific activity with the vertical dashed lines indicating the first, second, third, and fourth quartiles of the population. A shows that the predominance of high specific activities above an arbitrarily selected threshold level of 4% (whose clinical relevance is defined²⁷) in the low total serum IgE range from 20 to 5000 kU/L. B shows in a different format that the probability of obtaining a high IgE specific activity²⁶ (eg, >4%) increases progressively with decreasing total serum IgE concentration. Reproduced with permission from Hamilton RG, McGlashan DW, Saini SS. IgE antibody specific activity in human allergic disease.