Systemically induced photoallergy to quinine in the mouse can be elicited topically--and vice versa.

Groups of female albino mice were photosensitized and photochallenged to quinine using protocols for either systemic or epicutaneous administration. Compared with control groups, statistically significant inflammatory reactions, measured as wet weight increase in ear tissue, could be obtained both with systemic and epicutaneous administration. Topically induced photoallergy to quinine could be elicited not only by topical, but also by intraperitoneal administration of the drug, and vice versa. The strongest response at challenge was obtained when the induction was performed topically and the challenge by the systemic route. These data suggest that epicutaneous and systemic photoallergy to quinine have mechanisms in common, and that the route of introduction of the sensitizer into the skin is not the crucial factor. This experimental model may be useful in the elucidation of the mechanisms of systemic photoallergy.