Di-(2-ethylhexyl) phthalate is without adjuvant effect in mice on ovalbumin

It has been suggested that one possible contributor to the increasing prevalence of IgE-mediated allergic diseases in Europe and the US is exposure to chemicals that may act as adjuvants. It has been reported previously that certain commonly used phthalate plasticizers, such as di-(2-ethylhexyl) phthalate (DEHP), are able to modify immune responses induced in mice by the common hens' egg allergen ovalbumin (OVA). However, the significance of these observations for human health is unclear, not least because the relevant studies have been conducted exclusively using subcutaneous administration of phthalates. We have therefore investigated the ability of DEHP when applied topically to affect anti-OVA antibody responses induced by subcutaneous exposure to OVA in BALB/c strain mice. Doses of DEHP (50mg) were used that resulted in a marked (approximately 30%) increase in liver weight. Dose-responses were conducted in order to identify doses of OVA that were sub-optimal for both anti-OVA IgG1 and IgE antibody responses: 1microg and 0.05microg, respectively. Under these conditions of exposure, topical administration of DEHP was without impact on antibody responses, regardless of whether DEHP was applied local or distant to the site of OVA immunization. Topical application of concentrations of DEHP that provoked marked systemic effects was without effect on the induction of immune responses.