Rattis F M, Péguet-Navarro J, Courtellemont P, Redziniak G, Schmitt D
Laboratoire Peau Humaine et Immunité, INSERM U346, Hôpital E. Herriot, Lyon, France.
Photochem Photobiol. 1995 Nov;62(5):914-6. doi: 10.1111/j.1751-1097.1995.tb09155.x.
Urocanic acid (UCA) represents the major ultraviolet B (UVB, 290-320 nm)-absorbing component of the skin. Trans-UCA is naturally produced in the stratum corneum and converts to the cis isomer upon UVB irradiation. In this study, we examined the effect of purified cis-UCA (about 99% of cis isomer) on the human Langerhans cell (LC) allostimulatory function by using the mixed epidermal cell-lymphocyte reaction (MELR). We found that addition of increasing amounts (6.5-400 micrograms/mL) of purified cis-UCA or trans-UCA did not modify the T-cell response supported by enriched LC (eLC: 8-25% LC) as well as purified LC (pLC: 70-90% LC) suspensions. Because cis-UCA had no effect on the allostimulatory function of untreated LC, we investigated whether this compound could modify T-cell proliferation induced by UVB-irradiated LC. The UVB exposure of eLC or pLC to 100 J/m2 significantly inhibited the capacity of both suspensions to mount a T-cell response. However, addition of cis-UCA did not potentiate this UVB-induced immunosuppression. The eLC or pLC were then incubated with cis-UCA for 18 h at 37 degrees C and washed before adding to allogeneic T cells. The obtained proliferative response was similar to that induced by control LC incubated in medium alone, demonstrating that pretreatment with cis-UCA did not alter human LC function. In conclusion, these results strongly suggest that cis-UCA has no direct effect on human LC antigen-presenting function.
尿刊酸（UCA）是皮肤中主要吸收紫外线B（UVB，290 - 320纳米）的成分。反式UCA在角质层中天然产生，并在UVB照射后转化为顺式异构体。在本研究中，我们通过混合表皮细胞 - 淋巴细胞反应（MELR）研究了纯化的顺式UCA（约99%的顺式异构体）对人朗格汉斯细胞（LC）同种异体刺激功能的影响。我们发现，添加递增剂量（6.5 - 400微克/毫升）的纯化顺式UCA或反式UCA并不会改变富集LC（eLC：8 - 25% LC）以及纯化LC（pLC：70 - 90% LC）悬液所支持的T细胞反应。由于顺式UCA对未处理的LC的同种异体刺激功能没有影响，我们研究了该化合物是否能改变UVB照射的LC诱导的T细胞增殖。将eLC或pLC暴露于100 J/m²的UVB下显著抑制了两种悬液引发T细胞反应的能力。然而，添加顺式UCA并没有增强这种UVB诱导的免疫抑制作用。然后将eLC或pLC与顺式UCA在37℃下孵育18小时，洗涤后再加入同种异体T细胞。所获得的增殖反应与仅在培养基中孵育的对照LC诱导的反应相似，表明用顺式UCA预处理不会改变人LC的功能。总之，这些结果强烈表明顺式UCA对人LC的抗原呈递功能没有直接影响。
