TOPICAL EXPOSURE TO CHLORDANE REDUCES THE CONTACT HYPERSENSITIVITY RESPONSE TO OXAZOLONE IN BALB C MICE/

Previous studies have shown that prenatal exposure to the organochlori ne pesticide chlordane significantly decreases the ear swelling respon se to the contact allergen oxazolone in BALB/c mice, Alterations of ma crophage function in the efferent arm of the contact hypersensitivity response have also been reported. In the current study, chlordane was applied topically and the effects of oxazolone-induced contact hyperse nsitivity were determined, Initially, the reduction in oxazolone-induc ed ear swelling in topically-exposed female BALB/c mice was compared t o 30-day-old BALB/c female mice exposed prenatally to chlordane, Prena tal chlordane exposure induced a 36% reduction in ear swelling compare d to a 60% reduction following topical treatment at the challenge phas e, Topically-applied chlordane also reduced the oxazolone-induced ear swelling by 40% when applied at sensitization. When applied at both se nsitization and challenge, ear swelling was reduced by 71%. In a time- course study, it was determined that chlordane must be applied at the time of sensitization, challenge or both or within 1 h post-challenge to significantly reduce ear swelling. A dose-response study showed tha t the lowest concentration of chlordane resulting in a significantly r educed ear swelling response was 20 mu g per ear.