THE VEHICLE MODULATES CELLULAR AND HUMORAL RESPONSES IN CONTACT HYPERSENSITIVITY TO OXAZOLONE

The development of contact hypersensitivity (CHS) greatly depends on t he allergenicity of the inducing agent. However, various cofactors are known to influence the outcome of the response as well. From this per spective, we have compared the effects of five different vehicles: ace tone, ethanol, dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), an d a 4 to 1 mixture of acetone and olive oil (AOO) on the cellular and humoral immune responses to epicutaneously applied oxazolone in female BALB/c mice, A single application of 0.2% oxazolone dissolved in acet one or ethanol induced stronger proliferative responses and higher lym ph node cell numbers than the other three vehicles. Moreover, both veh icles led to higher numbers of oxazolone-specific Ab forming cells in the draining lymph nodes of sensitized animals. When the IgG2a/IgG1 ra tios were determined to indicate the type of T helper cell involved, t he highest values were obtained with AOO and lowest with DMF and DMSO, while acetone and ethanol were in between. Moreover, no correlation w as found between oxazolone-specific antibody production and cellular r esponses, measured as [H-3]thymidine incorporation of draining lymph n ode cells after sensitization and increased ear thickness after challe nge. From this study it can be concluded that cellular and humoral res ponses in CHS to oxazolone are dissimilarly affected by the vehicles u sed. (C) 1998 Society of Toxicology.