A new animal model for contact dermatitis: the hairless guinea pig.

Allergic and irritant contact reactions were evaluated in the recently identified hairless guinea pig, Crl:IAF(HA)BR, a mutant from the Hartley strain. The cutaneous changes were observed macro- and microscopically. The irritant contact dermatitis was induced by croton oil, 2,4-dinitrochlorobenzene (DNCB), or anthralin. Both hairless and hairy guinea pigs developed similar reactions to these chemicals. The density of the epidermal Langerhans cells (LC) of hairless guinea pigs was significantly higher than that in the hairy strain. Allergic contact sensitization was easily induced with DNCB. Photoallergic contact sensitization was also induced with tetrachlorosalicylanilide (TCSA) but not with tribromosalicylanilide (TBS). However, by administration of cyclophosphamide before sensitization, positive photocontact responses were seen with TBS. These results indicate that hairless guinea pigs can be used as animal models for investigation of immunologic and nonimmunologic contact reactions.