IN-VITRO EVALUATION OF CONTACT SENSITIVITY TO DNCB USING HAPTEN-STIMULATED IN-VITRO INTERLEUKIN-2 PRODUCTION BY MURINE LYMPH-NODE CELLS

Contact sensitizers are considered to lead to an immune response chara cteristic of Th1-type T helper cell activation, and interleukin-2 (IL- 2) is a representative cytokine secreted by Th1 cells. In this study, contact sensitivity to 1-chloro-2,4-dinitrobenzene (DNCB) was evaluate d using hapten-stimulated in vitro IL-2 production by the lymph node c ells from mice contact-sensitized to DNCB. IL-2 activity in 48-h cultu re supernatants was measured by its ability to stimulate IL-2-dependen t CTLL-2 cell growth using -(4,5-dimethylthiazol-xyl)-2,5-diphenyltetr azolium colorimetric assay, expressed as stimulation index. The result s showed that DNCB-induced in vitro IL-2 production by the murine lymp h node cells was hapten-specific. The peak of in vitro IL-2 production was observed on the 7th day after contact sensitization in mice. Ther e was also a cross-reaction between DNCB and 2,4-dinitrobenzene sulfon ic acid (DNBS) in in vitro IL-2 production. Strong dose-response relat ionships for DNCB-specific in vitro IL-2 production and for the cross- reaction to DNBS were further demonstrated. In addition, there was a g ood correlation between DNCB-induced in vitro IL-2 production and in v ivo contact hypersensitivity as evaluated by mouse ear-swelling respon ses. Thus, the results suggest that hapten-stimulated in vitro IL-2 pr oduction by murine lymph node cells may be useful for predicting the c ontact-sensitizing capacity of chemicals.