Comparative Study for the Dif ferent iat ion of A l le rg ic and I r r i tant Contact Dermati t is in Micet

= A bst rac t =Our study was performed t o compare the differences between allergic and irritant contact dermatitis in BALB/c mice. Allergic reaction was induced by a sensitizing regimen of 2,4-dinitro-1-fluorobenzene (DNFB) and irritant reaction by 10% sodium lauryl sulfate (SLS). The following differences were noted: 1) the mice with irritant reaction showed an earlier peak of ear swelling, 2) increasing number of Langerhans cells (LCs) in allergic reaction but decreasing number of LCs in irritant reaction was observed a t 48 hr after challenge of DNFB or SLS, and 3) induction of Ia (+) keratinocytes was found only in allergic reaction. It was suggested that Ia (+) keratinocytes play an active role in the mechanism of allergic contact dermatitis.