Reduced frequency of atopic dermatitis in quinoline-allergic patients: the 'hapten-atopy hypothesis'.
BACKGROUND
While allergy to food proteins is almost exclusively found in association with atopy, it has been our experience that contact allergy to some contact allergens/haptens with both cutaneous and gastrointestinal exposures is reduced in atopic dermatitis (AD) patients as a group.


OBJECTIVE
To assess the contact allergy rates of two classes of antimicrobial haptens, one with both cutaneous and gastrointestinal exposures (quinolines) and one with only significant cutaneous exposure (aminoglycosides), with respect to the presence or absence of AD.


METHODS
Contact allergy rates to neomycin (aminoglycoside) and quinoline mix/clioquinol in patients attending the St John's Institute of Dermatology for diagnostic patch testing were retrospectively analysed; current AD and history of AD were noted.


RESULTS
In comparison to neomycin-allergic subjects, there was a highly significant negative association between quinoline contact allergy and current presence of AD (P = 0.0028); negative association between quinoline contact allergy and a history of AD did not reach significance (P = 0.07).


CONCLUSIONS
In comparison to an antimicrobial with no significant gastrointestinal exposure (neomycin), contact allergy to quinolines is negatively associated with the presence of AD. This is in contrast to food protein allergy, which is strongly associated with atopy. Possible explanations could include (i) confounding factors or (ii) AD patients are efficient at orally tolerizing haptens and inefficient at orally tolerizing proteins, secondary to their atopic status or (iii) oral tolerance of haptens antagonizes tolerance of food proteins and also leads to an immunological shift towards atopy (hapten-atopy hypothesis).
McFadden
John P
JP
Department of Cutaneous Allergy, St John's Institute of Dermatology, St Thomas' Hospital, London SE1 7EH, UK. john.mcfadden@kcl.ac.uk
White
Jonathan M L
JM
D000293:Adolescent; D000328:Adult; D000890:Anti-Infective Agents / Q000009:adverse effects / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D017449:Dermatitis, Allergic Contact / Q000453:epidemiology* / Q000209:etiology / Q000276:immunology; D003876:Dermatitis, Atopic / Q000453:epidemiology* / Q000276:immunology; D004333:Drug Administration Routes; D005260:Female; D041981:Gastrointestinal Tract / Q000276:immunology; D006241:Haptens / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D007223:Infant; D008297:Male; D008875:Middle Aged; D009355:Neomycin / Q000009:adverse effects / Q000276:immunology; D010328:Patch Tests; D015363:Quinolones / Q000009:adverse effects / Q000276:immunology*; D012189:Retrospective Studies; D012867:Skin / Q000276:immunology / Q000473:pathology
D000890:Anti-Infective Agents; D006241:Haptens; D015363:Quinolones; D009355:Neomycin