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Is benzoquinone the prohapten in cross‐sensitivity among aminobenzene compounds?
Author(s) -
Lisi Paolo,
Hansel Katharina
Publication year - 1998
Publication title -
contact dermatitis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 96
eISSN - 1600-0536
pISSN - 0105-1873
DOI - 10.1111/j.1600-0536.1998.tb05945.x
Subject(s) - chemistry , sensitization , hapten , benzoquinone , hydroquinone , patch test , p phenylenediamine , contact dermatitis , allergic contact dermatitis , benzocaine , medicinal chemistry , allergy , organic chemistry , antigen , immunology , medicine
Cross‐sensitivity in allergic contact dermatitis is a simultaneous allergy to 2 or more contact substances which have in common an antigenic determinant or a metabolic derivative. One of the most notable examples is the cross‐sensitivity among aromatic compounds which may be oxidized in vivo to benzoquinone (BQ). However, it has also been hypothesized that the allergenicity and cross‐sensitization are modulated by the chemical reactivity of the substituents in the para position. A serial dilution of BQ (from 1% to 0.1% in pet.) and three 1,4‐substituted benzene derivatives ( p ‐aminophenol, hydroquinone, metol), theoretically capable of conversion to BQ by oxidation, were patch tested in 22 p ‐phenylenediamine (PPD) positive patients and in 20 controls. The patients and a further 116 subjects with a positive history of sensitivity to 1 or more aminoaromatic compounds were also tested with some haptens of the para group (PPD, p ‐aminobenzoic acid, p ‐aminodiphenylamine, benzocaine, procaine chloride, p ‐toluenediamine sulfate). The results show that (i) the optimal patch test concentration for BQ was 0.2%, (ii) only 4 of the 22 patients allergic to PPD gave a clearly positive allergic reaction to BQ, and (iii) the number of positive reactions to the aromatic compounds was correlated with the presence of activating (‐NH 2 , ‐OH, ‐CH 3 ) and deactivating (‐COOH) groups in the para position or, perhaps, with their effect on percutaneous penetration. The data suggest that BQ is not the only intermediate in the cross‐sensitization of para group haptens. This is probably conditioned by other oxidation products and/or the chemical structure of the substituents in position 4 of the benzene ring.