The application of the sepharose bead immunofluorescence test for the detection of allergen-specific IgE and IgG antibodies in pollinosis

Abstract

A new application of the Sepharose bead immunofluorescence test for detection of allergen-specific IgE and IgG antibodies is described. Allergen extracts of four different grass pollens were coupled to CNBr-activated Sepharose 4B. Twenty normal and allergic sera were incubated with the allergen-coupled beads, washed and incubated with fluorescence-conjugated anti-gamma E and G globulins. After washing and staining with 0.5% trypan blue, the percentage of fluorescent beads was detected by fluorescence microscopy. In the IgG/anti IgG system, the smallest amount of IgG demonstrated was 20ng/ml; in the IgE/anti-IgE system it was 40ng/ml. Independent examination of tests gave a mean difference between observations of 4.1%. Reproducibility was also very good (var. coeff = 18%). The number of beads stained with IgE correlated well with intensity of skin reactions to the same extracts (r = 0.64; p = 5 x 10-7), the percentage of IgG stained beads being independent of skin reactivity. The Sepharose-IgE test allowed clear distinction between allergic and normal sera (p = 4 x 10-7), while the Sepharose IgG test did not distinguish between them at the time of diagnosis. However, the number of beads stained with IgG significantly increased in patients undergoing immunotherapy (p = 3.8 x 10-3). The Sepharose bead immunofluorescence test requires a very small amount of materials, is highly sensitive and easy to handle. It may be valuable in the "in vitro" diagnosis of grass pollen allergy and useful in evaluating immunotherapy.