Influence of the medium on the heat and acid denaturation of IgE.

The denaturation of IgE immunoglobulin induced by heating at 56 degrees C or by treatment at low pH is inhibited in the presence of high concentrations of salts or hexoses. Between 50 and 100% of the IgE anaphylactic activity (PCA) of rat and mouse antisera is recovered after heating at 56 degrees C for 1,5 or 5 h, respectively, in 1 M MgSO4 or 2 M glucose, mannose or fructose. Anaphylactic activity of IgE monoclonal anti-DNP mouse antibody is equally preserved. The specific antigenic determinants of human and rat IgE myeloma proteins are also thermostable in these conditions. The addition of MgSO4 or glucose protects IgE anaphylactic antibodies against denaturation at pH 2. It is suggested that IgE denaturation is the consequence of interactions between molecules of immunoglobulin and that such interactions are diminished by steric hindrance in a medium containing high concentrations of ions or hexose molecules.