Development of a semiautomated microassay for bovine immunoglobulin E: definition and standardization.

Although the serum immunoglobulin (Ig) E concentration is a critical and valuable measurement in parasitic infections and allergic diseases, little has been reported on it in cattle. We have developed an enzyme-linked immunosorbent assay to measure serum concentrations of bovine IgE. This assay was developed and standardized, using the statistical guidelines of the Bureau of Biological Standardization of National Institutes of Health. A reference serum used to standardize results was assigned a value of 100 IgE U/ml. Absorbance values for test samples were converted into IgE units by comparison with a standard curve, generated by dilutions of this reference serum. Serum samples from 160 adult cows and calves had a geometric mean of 17.8 IgE U/ml. The IgE values were higher in calves from parasite-infested pastures than in parasite-free calves and adult cows. This assay is the first procedure appropriate for multiautomated analysis of IgE in cattle.