The IgE Antibody Combining Site

The authors concluded that unlike most drug allergic determinants the whole chlorhexidine molecule is complementary to the IgE antibody combining sites and that the 4-chlorophenol, biguanide, and hexamethylene structures together comprise the allergenic component. 

Many of the reactions to sulfonamides involve the skin and mucous membranes. The more severe reactions that occur include potentially lethal toxidermias and a delayed hypersensi-tivity-type syndrome characterized by fever, skin rash, and multi-organ toxicity, hnmediate type I reactions are the most well-defined sulfonamide-induced hypersensitivity reactions with the best defined allergenic drug structmes. Sulfonamides with one methyl substituent on a five- or six-membered aromatic heterocyclic ring on the carbon p to the sulfon-amido substituent are the structmes most complanentary to anti-sulfamethoxazole IgE antibody combining sites. 

A specific assay to detect IgE antibodies to the drug has been developed. The structure shown to be most complanentary to the antibody combining sites was the entire chlorhexidine molecule. 

Almost all reports of trimethoprim-induced hypersensitivities are of the immediate kind. At least three different trimethoprim allergenic determinant structures complementary to the combining sites of trimethoprim-reactive IgE antibodies have been identified. One of the determinants, the 3,4-dimethoxybenzyl structure represents one-half of the trimethoprim molecule the other two comprise structures that make up the entire, and almost the entire, molecule. 

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