Identification of IgG antibody as a carrier of reaginic activity in asthmatic patients.

In a previous study it was reported that a group of asthmatic patients, in whom cromolyn sodium did not inhibit bronchial immediate allergic reactions, had reaginic antibodies that did not appear to belong to the IgE class. This study was designed to extend these observations, and it was shown that the IgG fractions from these patients' sera, purified by ion exchange chromatography and specific immunosorbents, had skin-sensitizing activity to the antigen studied, while the IgE fractions did not. The skin-sensitizing activity in the IgG fractions was not removed by anti-IgE antiserum and was not inactivated by heating at 56 degrees C or by reduction/alkylation. It is proposed that IgG antibodies may mediate immediate allergic reactions in some asthmatic patients, that these patients can be detected by means of serum total IgE and allergen-specific IgE estimation, and that cromolyn sodium is not an effective inhibitor of bronchial immediate allergic reactions in these patients.