COMPARISON OF SENSITIZING PROTOCOLS FOR ULTRAVIOLET B-INDUCED IMMUNOSUPPRESSION IN C3H MICE

To compare previously used protocols for ultraviolet (UV)-induced supp ression of contact hypersensitivity in mice, and to develop an optimiz ed protocol for C3H mice, the effect of 3 different allergens, varying allergen concentrations in the induction or challenge phase, local an d distant sites of allergen application in respect to irradiation site , 2 mouse substrains and 2 different light sources was studied. A conc entration of 0.5% of oxazolone (OXA) gave a slightly better contact se nsitization than a 1% concentration of trinitrochlorobenzene (TNCB). T itration experiments revealed that for both OXA and TNCB, a 1% sensiti zation concentration was optimal, while the optimal challenge concentr ation was 0.5% for OXA and 1% for TNCB. The magnitude of the resulting contact sensitization was not influenced by either the mouse substrai n (C3H/HeJ or C3H/HeN) or the site of allergen application (back or be lly), but application of fluorescein isothiocyanate to the ears only p roduced weak sensitization. A standard UVB dose of 1.3 kJ/m2 suppresse d TNCB contact sensitivity to a greater extent than that of OXA. A sim ilar degree of UV-induced suppression was obtained with a given UVB do se, irrespective of a 50-fold difference in the concomitant UVA dose. Based on our results, a proper protocol of contact sensitization for U V-induced immunosuppression in C3H mice includes sensitization with 0. 5% OXA on either the mouse back or belly, ear challenge with 0.5% OXA and ear swelling reading 24 h after challenge.