title: Experimental photoallergy to systemic drugs.
abstract: We have induced photoallergy in mice to systemically administered drugs, specifically sulfanilamide and chlorpromazine. Mice were photosensitized to systemic sulfanilamide or chlorpromazine by i.p. administration of drug followed by UVB and UVA irradiation of shaved flank skin, on two consecutive days. Control mice received i.p. drug with no irradiation. In some experiments cyclophosphamide pretreatment, or intradermal Corynebacterium parvum (Propionibacterium acnes), was administered as an immunoadjuvant. All animals were photochallenged on day 5 with i.p. drug followed by UVA irradiation of one ear. Mice that had been previously immunized with drug and UV radiation developed ear swelling and erythema, evident 24 h after photochallenge, but not at 4 h. Control animals showed no reactions. In a typical experiment of photosensitization to systemic sulfanilamide, the experimental group had a mean increase in ear thickness of 6.0 X 10(-2) mm 24 h after photochallenge, while unsensitized control animals showed a mean change of -0.8 X 10(-2) mm. The histopathology of the positive challenge reaction was characteristic of a delayed type hypersensitivity. Adoptive transfer of photoallergy to systemic sulfanilamide to naive recipients was accomplished by i.v. injection of lymph node cells (5 X 10(7) harvested from actively photosensitized donors. Clinical reports have suggested that exposure to systemic medications followed by sunlight can induce an eruption having a photoallergic basis. We now report the first experimental proof of that hypothesis. The murine model should facilitate exploration of photoallergic mechanisms and, in addition, it provides the basis for a prospective test of systemic drugs for their photoallergenicity.
mesh_terms: D000818:Animals; D002746:Chlorpromazine / Q000008:administration & dosage* / Q000009:adverse effects; D004195:Disease Models, Animal; D006968:Hypersensitivity, Delayed / Q000473:pathology; D007274:Injections, Intraperitoneal; D051379:Mice; D008807:Mice, Inbred BALB C; D010787:Photosensitivity Disorders / Q000139:chemically induced* / Q000473:pathology; D012867:Skin / Q000528:radiation effects; D013424:Sulfanilamides / Q000008:administration & dosage* / Q000009:adverse effects; D014466:Ultraviolet Rays
chemical_list: D013424:Sulfanilamides; D002746:Chlorpromazine