INFLUENCE OF DIBUTYL PHTHALATE ON DERMAL SENSITIZATION TO FLUORESCEINISOTHIOCYANATE

What limited evidence there is indicates that the formulation in which a chemical allergen is encountered on the skin can have a marked impa ct upon the induction of cutaneous immune responses and the subsequent development of contact sensitization. The purpose of the present inve stigations was to examine further this phenomenon by analysis of the i nfluence of dibutyl phthalate (DBP) on dermal sensitization to fluores cein isothiocyanate (FITC), a skin sensitizing fluorochrome. Addition of DBP augmented very substantially, in a dose-dependent fashion, the ability of topically applied FITC to stimulate proliferative responses in mice by draining lymph node cells (LNC), a correlate of skin sensi tizing potential. Under these conditions, exposure of mice to DBP alon e failed to elicit significant LNC responses. The influence of DBP on the accumulation of dendritic cells (DC) induced by FITC was examined also, Although 10% DBP had little effect on the numbers of DC found wi thin draining nodes 18 hr following exposure of mice to FITC, the phth alate did result in a very substantial increase in the frequency of ly mph node DC bearing detectable antigen (FITC+ DC). Furthermore, in the presence of DBP the median amount of FITC associated with antigen-bea ring DC was higher. In vitro skin absorption studies indicated that DB P was associated with a small increase in percutaneous absorption of F ITC, Collectively these data demonstrate that the vehicle formulation can exert a marked influence on dermal sensitization and that one mech anism which may be relevant is the increased acquisition of antigen by DC, associated possibly with altered penetration of the allergen into or through the skin. (C) 1996 Society of Toxicology