ABSTRACT
Guinea pigs are a classic animal model for studying delayed-type hypersensitivity (DTH) reactions. However, skin irritation due to hair removal can interfere with the evaluation of the modulation of these responses by various mediators. A DTH model using hairless (IAF/HA-HO) guinea pigs, sensitized with complete Freund's adjuvant and repeatedly skin tested with tuberculin, purified protein derivative, (PPD) has therefore been developed. At 10 weeks after sensitization, intradermal PPD elicited minimal erythema at 6 h, which increased over the next 18 h to a maximum at 24 h, and declined by 48 h. The response could be quantified by bioassay using graded doses of PPD. Reactions at 24 h were characterized by predominantly mononuclear cell deep and superficial dermal infiltrates. Dermal DTH in hairless guinea pigs is thus, grossly and histologically similar to that seen in Hartley guinea pigs.
