Enzyme immunoassay of specific human IgE to purified cows' milk allergens

An immmunometric enzyme immunoassay for specific immunoglobulin E (IgE) against five purified cows' milk allergens, beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin, lactoferrin and whole casein fraction, has been developed. Allergens were immobilized on microtitration plates. After incubations with sera from allergic patients, specific IgE bound to the plastic were detected using a monoclonal anti-human IgE antibody labelled with acetylcholinesterase. Quantitative determinations were made by comparison with a dose response curve obtained under the same conditions with standard total IgE. A quantification limit of 0.08 IU ml(-1) can thus be obtained with a coefficient of variation of lower than 5%. This allows specific IgE determinations of clinical significance in sera from allergic patients at a dilution of at least 1/10 (i.e. in a few mu l of serum) with good precision and reproducibility. The determinations of specific IgE in sera from 11 patients allergic to cows' milk showed an excellent correlation of this assay with clinical data.