Ulrich P, Homey B, Vohr H W
Experimental Toxicology, Novartis Pharma AG, Basel, Switzerland.
Toxicology. 1998 Feb 6;125(2-3):149-68. doi: 10.1016/s0300-483x(97)00156-x.
Since predictive differentiation of photoallergenic from phototoxic reactions, induced by low molecular weight compounds, represents a current problem, we tried to improve the differentiation between the two reactions by using a modified protocol of the local lymph node assay (LLNA). Briefly, groups of female BALB/c mice received compound solution or vehicle alone on the dorsum of both ears on 3 consecutive days. Immediately after compound application indicated groups of mice were exposed to a UVA light-dose of 10 J/cm2. Auricular lymph nodes draining the ear tissue were excised 24 h following the last exposure. Evaluation consisted of assessing lymph node weights and cell counts to monitor organ hyperplasia and in vivo-proliferative events following substance application. Furthermore, we analysed cytokine gene transcription in freshly prepared lymph node cells (LNC) and the cytokine release in vitro by restimulated CD4+ T-cells and antigen presenting cells (APC), both purified from the skin-draining lymph nodes. Both contact (photo) allergenic (oxazolone and tetrachlorosalicylanilide) and phototoxic substances (8-methoxypsoralen and acridine) caused a dose dependent increase in lymph node weights and cell counts pointing to an inflammatory process in the lymph nodes. Analysis of cytokine gene transcription ex vivo and cytokine release in vitro revealed that during the induction phase of contact (photo) allergy CD4+ T-cells produced IL-2 and IFN-gamma as well as IL-4 and IL-10, whereas IL-6 was derived from APC. In contrast, phototoxic reactions caused only an upregulation of IL-2 and IFN-gamma. Furthermore, we demonstrate that the release of IL-4 and IL-10 by CD4+ T-cells was clearly increased, whereas IL-6 and IFN-gamma expression was reduced or not changed following a challenge with contact (photo) allergens revealing an allergy-indicative shift in cytokine expression. In conclusion, our results show that contact photoallergenic reactions could be differentiated from phototoxic events by analysis of LNC cytokine expression patterns.
由于区分低分子量化合物诱导的光变应性反应与光毒性反应是当前的一个问题，我们尝试通过使用改良的局部淋巴结试验（LLNA）方案来改善这两种反应之间的区分。简而言之，将雌性BALB/c小鼠分组，连续3天在双耳背部分别给予化合物溶液或单独的赋形剂。在涂抹化合物后，立即对指定组的小鼠给予10 J/cm2的UVA光剂量照射。在最后一次照射后24小时切除引流耳部组织的耳淋巴结。评估包括评估淋巴结重量和细胞计数，以监测物质应用后器官增生和体内增殖事件。此外，我们分析了新鲜制备的淋巴结细胞（LNC）中的细胞因子基因转录以及从引流皮肤的淋巴结中纯化的再刺激CD4+ T细胞和抗原呈递细胞（APC）在体外释放的细胞因子。接触性（光）变应原（恶唑酮和四氯水杨酰苯胺）和光毒性物质（8-甲氧基补骨脂素和吖啶）均导致淋巴结重量和细胞计数呈剂量依赖性增加，表明淋巴结存在炎症过程。体外细胞因子基因转录分析和细胞因子释放分析表明，在接触性（光）过敏的诱导阶段，CD4+ T细胞产生IL-2、IFN-γ以及IL-4和IL-10，而IL-6来源于APC。相比之下，光毒性反应仅导致IL-2和IFN-γ上调。此外，我们证明，在用接触性（光）变应原激发后，CD4+ T细胞释放的IL-4和IL-10明显增加，而IL-6和IFN-γ表达降低或未改变，这表明细胞因子表达出现了过敏指示性转变。总之，我们的结果表明，通过分析LNC细胞因子表达模式，可以区分接触性光变应性反应与光毒性事件。
