Photopatch test (PhPT) interpretation is difficult and clinical relevance is n ot always apparent. A positive PhPT may reflect photocontact allergy or phototox icity. We hypothesized that it may also reflect the addit...Photopatch test (PhPT) interpretation is difficult and clinical relevance is n ot always apparent. A positive PhPT may reflect photocontact allergy or phototox icity. We hypothesized that it may also reflect the additive or synergistic effe cts of a suberythemal reaction to a contact irritant [e.g. sodium lauryl sulfat e (SLS)] or allergen (e.g. nickel) and suberythemal UV exposure. 10 nickel aller g ic volunteers had duplicate SLS and nickel series applied on either side of the back for 24 h and 48 h, respectively. After removal, one side was irradiated wit h 5J/cm2 UVA or the dose below the minimal erythema dose for solar-simulated ra diation (SSR). The minimal irritancy dose (MID) for SLS and the minimal allergen ic dose (MAD) for nickel were determined visually and objectively by erythema me ter. While photoaugmentation of subclinical contact allergy or irritancy occurre d in some subjects, photosuppression occurred in roughly an equal number. UVA ch anged the nickel MAD at 48 h in 2 of 5 volunteers but not the SLS MID. SSR chang ed the nickel MAD in 4 of 5 and the SLS MID in 3 of 5. 2 subjects (none after UV A) showed erythema only in the irradiated set of p atches, which could have been interpreted as a positive PhPT. We have demonstrat ed photoaugmentation and photosuppression of contact allergy and irritancy, whic h could result in false-positive or false-negative interpretation of PhPTs.展开更多
文摘Photopatch test (PhPT) interpretation is difficult and clinical relevance is n ot always apparent. A positive PhPT may reflect photocontact allergy or phototox icity. We hypothesized that it may also reflect the additive or synergistic effe cts of a suberythemal reaction to a contact irritant [e.g. sodium lauryl sulfat e (SLS)] or allergen (e.g. nickel) and suberythemal UV exposure. 10 nickel aller g ic volunteers had duplicate SLS and nickel series applied on either side of the back for 24 h and 48 h, respectively. After removal, one side was irradiated wit h 5J/cm2 UVA or the dose below the minimal erythema dose for solar-simulated ra diation (SSR). The minimal irritancy dose (MID) for SLS and the minimal allergen ic dose (MAD) for nickel were determined visually and objectively by erythema me ter. While photoaugmentation of subclinical contact allergy or irritancy occurre d in some subjects, photosuppression occurred in roughly an equal number. UVA ch anged the nickel MAD at 48 h in 2 of 5 volunteers but not the SLS MID. SSR chang ed the nickel MAD in 4 of 5 and the SLS MID in 3 of 5. 2 subjects (none after UV A) showed erythema only in the irradiated set of p atches, which could have been interpreted as a positive PhPT. We have demonstrat ed photoaugmentation and photosuppression of contact allergy and irritancy, whic h could result in false-positive or false-negative interpretation of PhPTs.
