Epidermal cell-contra-interleukin 1 inhibits human accessory cell function by specifically blocking interleukin 1 activity

Prevention of ultraviolet radiation-induced suppression of accessory cell function of Langerhans cells by Aloe vera gel components

The active components of Aloe vera gel that can prevent ultraviolet B (UVB)-induced suppression of accessory cell function of Langerhans cells (LC) were purified by activity-guided sequential fractionation followed by in vitro functional assay. The functional assay was based on the fact that exposure of freshly isolated murine epidermal cells (EC) to UVB radiation resulted in impairment of accessory cell function of LC, as measured by their ability to support anti-CD3 monoclonal antibody (mAb)-primed T-cell mitogenesis. This UVB-suppressed LC accessory cell function was prevented by addition of partially purified Aloe gel components to cultures of UVB-irradiated EC. The Aloe gel components appeared to prevent events occurring within the first 24 h after UVB irradiation that lead to the impairment of accessory cell function. The Aloe gel components did not cause proliferation of anti-CD3 mAb-primed T-cells, nor did induce proliferation of normal EC. The activity-guided final purification of Aloe gel components resulted in the isolation of two components. Both of the components were small molecular weight (MW) substances with an apparent MW of less than 1,000 Da but different from each other in net charge characteristics at pH 7.4. These results suggest that Aloe vera gel contains at least two small molecular weight immunomodulators that may prevent UVB-induced immune suppression in the skin.

Roles of CD4+ and CD8+ cells in UVB-induced suppression of splenic alloantigen-presenting function

Whole body ultraviolet light (UV) radiation causes systemic immunosuppression. Splenic antigen-presenting cell (APC) activity is decreased by UV radiation. To determine whether splenic CD4+ or CD8+ cells are involved in the UV-induced depression of splenic alloantigen-presenting function, we investigated the effect of in vivo UV radiation on the splenic stimulatory function in allogeneic mixed lymphocyte reaction in mice after the elimination of CD4+ or CD8+ cells by administering anti-CD8 or anti-CD4 Ab. Ab-treated and non-treated mice were exposed to UVB radiation (2.5 kJ/m2) twice or eight times. Two exposures to UVB radiation significantly suppressed the splenic alloantigen-presenting function of mice previously treated with anti-CD4 Ab, but hardly affected that of anti-CD8 Ab-treated or non-treated mice 2 days after the last radiation. On the other hand, eight exposures to UVB radiation suppressed this function in all mice. FACS analysis revealed that the UV-induced suppression is not associated with a significant decrease in the number of IA+ cell, as stimulator cells. It is suggested that CD4+ cells are somewhat preventive of the UV-induced depression of splenic allo-antigen-presenting function.