Courtellemont, P., F. Rattis, D. Schmitt and J. Peguet-Navarro. Effects of Ultraviolet B Radiation on In Vitro Hapten T-Cell Sensitization by Human Langerhans Cells. Toxic. in Vitro 1998. 12: 343-351.

The deleterious effects of ultraviolet B radiation (UVB) on the antigen-presenting function of human epidermal Langerhans cells (LC) were studied by using the in vitro primary and secondary T-cell proliferative responses to the trinitrophenyl hapten (TNP) modified autologous LC. Increasing doses of UVB radiation (100-200 J/m²) induced a dose-dependent inhibition of the primary and secondary TNP-specific T cell response. However, this decreased T-cell proliferative response after UVB radiation, was strongly enhanced when freshly isolated LC, as compared with cultured LC, were used as antigen-presenting cells (APC), suggesting an impaired development of LC accessory function. Moreover, the exogenous addition of IL1b , TNFa , IL10 or their specific monoclonal antibodies neither modified nor reversed the immunosuppressive effect of UVB radiation. Even if the low doses of UVB radiation (100 and 200 J/m²) seemed to slightly affect HLA-DR synthesis, the antigen-presenting function of human LC cannot be related to the decreased expression of these molecules but might be associated with an impaired development of accessory molecules such as a downregulation of B7-2 antigen.