Thermoinactivation of human IgE: antigenic and functional modifications.

The thennoinactivation kinetics of IgE were studied in experimental models revealing the antigenic properties and the basophil-sensitizing capacity of these immunoglobulins. A pool of human sera containing anti-Dactylis gloinerata (Dg) IgE was heated from 5 mm up to 4 hr at 56°. The IgE antigenicity was tested by two polyclonal ¹²⁵I-labelled anti-IgE antibodies; one anti-IgE was specific of the whole Fc∊ region, while the other had a specificity restricted to the D∊2 domain. Radioimmunoassays showed that the D∊2 epitopes were more rapidly altered than the D∊1 epitopes. The capacity of IgE to bind to basophil Fc∊ receptors was assayed by passive sensitization experiments. Basophil sensitivity towards the Dg pollen extract was tested by histamine release experiments in the presence of this allergen. A progressive decrease in cell sensitivity was observed when IgE samples used for cell sensitization were heated for longer than 5 mm. Thermoinactivation kinetics of IgE revealed an unexpected increase in the apparent quantity and biological activity of IgE heated for 5 mm at 56°. This fact could be due to auto-anti-IgE antibodies linked to the unheated IgE and which interfere with the biological activities of lgE and their quantification. [ABSTRACT FROM AUTHOR]