Characterisation of the reaginic response to sulphonamides in mice

Reaginic responses were induced in immunised mice with either 4-sulphanilamidobenzoic acid (4-SABA) or sulphamethoxazole (SMX) coupled to chicken gamma-globulin (CGG). The former was coupled through the carboxylic group of benzoic acid and the latter through the diazo derivative of the sulphanilamide group. The specificity of the reaginic responses obtained was assessed in each case by inhibition of passive cutaneous anaphylaxis in the rat. Immunisation with 4-SABA-CGG resulted in antibodies which recognised the sulphanilamide group as immunodominant and, therefore, they cross-reacted strongly with other sulphonamides. In contrast, SMX-CGG-induced IgE antibodies directed primarily to the methoxazole end of the molecule and cross-reactivity with other sulphonamides could not be demonstrated. This model may be useful for a more comprehensive study of allergic reactions induced by sulphonamides.