SUBOPTIMAL NONINFLAMMATORY CONCENTRATIONS OF HAPTENS MAY ELICIT A CONTACT SENSITIVITY REACTION WHEN USED AS A MIX

Contact dermatitis is a cutaneous inflammatory reaction mediated by ha pten-specific T cells. We used a murine model to investigate the conta ct sensitivity reaction elicited by different concentrations (optimal and suboptimal) of the haptens DNFB and oxazolone applied singly or in combination. The simultaneous application of DNFB and oxazolone at op timal concentrations (0.2% and 0.4% respectively) did not significantl y increase the ear swelling response induced by each of the allergens when applied singly. No contact sensitivity response was observed when the haptens were tested individually at subthreshold concentrations ( 0.05% and 0.1% respectively). However, mixing the 2 molecules at the s ame concentrations gave rise to a clinical contact sensitivity reactio n. The simultaneous application of the haptens at a 2X higher, but sti ll suboptimal concentrations (0.1% and 0.2% respectively), elicited an inflammatory response that was significantly greater than the respons es elicited by either of the haptens when applied separately. These re sults suggest that a ''false-positive'' reaction to a mix may reveal a genuine sensitization to the constituents. (C) Munksgaard, 1996.