Contact hypersensitivity (CHS) is an epidermal T cell-mediated inflammatory response to low molecular weight haptens. CHS is executed by the recognition and capture of haptens by Langerhan’s cells (a type of dendritic cell which functions as skin antigen presenting cell (APC)). Langerhan’s cells present captured antigens to naive T cells, which leads to activation and clonal proliferation of inflammatory Th1 type cytokines (Watanabe et al., 2002), which mediates inflammatory immune disorders. In this study, we investigated the effect of topical application of aqueous fraction of porcine PE on experimental CHS responses and elucidated the mechanism of action. Topical application of porcine PE suppressed disease progression by down-regulation of serum level IgE and inflammatory cytokine production.