Chemical Structure and the Generation of an Allergic Reaction

Synonyms

Structure activity relationships, quantitative structure activity relationships.

Definition

The structure of a chemical and its associated physicochemical properties are fundamental determinants of the nature, type and degree of allergic reaction(s) that it may cause. Typically, chemicals which cause allergic reactions have a molecular weight in excess of 1000 Daltons, allowing ready penetration through epithelial surfaces, including the skin. However, exceptions do occur.

Characteristics

Chemicals must bind firmly with proteins in order to behave as haptens. For organic chemicals, this means the formation of covalent bonds; for the few allergenic metals (like nickel) the formation of coordination complexes is key. Extremely rarely-for example, for some drug allergens-tight interactions of organic chemical with protein, such as those encountered in ligand-receptor interactions, have been proposed. Thus the primary elements examined in relating structure to allergy are those...