二氯乙酸对淋巴细胞的毒性和CXCR2／3表达的作用

Cytotoxicity of dichloroacetic acid in lymphocyte and expression of chemokine receptor

目的探讨三氯乙烯及其代谢产物对淋巴细胞增殖的影响以及二氯乙酸在三氯乙烯药疹样皮炎发病过程中的作用。方法抽取健康人外周静脉血，分离淋巴细胞，分别在2h和4h检测0．020．05、0．10、0．20、0．50、1．00、2．00、5．00、10．00、20．00、30．00mmol／L共12个浓度二氯乙酸、三氯乙烯、三氯乙酸刺激培养的淋巴细胞增殖能力；通过中性红试验找到二氯乙酸的半数致死量（NR50），依据NR50检测细胞在不同浓度二氯乙酸刺激下乳酸脱氢酶（LDH）和超氧化物歧化酶（SOD）活力；采用实时荧光定量技术检测二氯乙酸刺激下体外培养的淋巴细胞CXCR2和CXCR3基因mRNA的表达情况。结果细胞增殖能力检测结果显示，20．00mmol／L二氯乙酸刺激时的细胞活力为50％，而30．00mmol／L三氯乙烯和三氯乙酸刺激的细胞活力仍保持在60％以上。与对照组相比，染毒4h时各剂量二氯乙酸刺激时SOD活力均明显降低，并且酶活力随剂量的升高呈下降趋势，差异均有统计学意义（P〈0．05）。第4h在0．88、1．75、3．50、7．00mmol／L二氯乙酸刺激时的LDH活力与第1h比较，差异均有统计学意义（P〈0．05）。在0．5、10．0mmol／L二氯乙酸刺激培养48h下，CXCR2和CXCR3基因mRNA的表达分别是对照细胞表达量的10．34、5．66倍和19．43、8．75倍，差异均有统计学意义（P〈O．01）。结论二氯乙酸对体外培养的淋巴细胞具有较强的毒性作用，可能是三氯乙烯药疹样皮炎的主要诱导剂。

Objective To explore the effects of triehloroethylene （TCE） and its by-products （trichloroacetic acid, TCA; dichloroacetic acid, DCA） on the normal human peripheral blood lymphocyte and the role of DCA in dermatitis medicamentosa- like induced by trichlorocthylene（DMLT）. Methods Lympho- cyte was isolated from peripheral venous blood, and cytotoxicity of human lymphocytes treated with different concentrations（0.02-30.00 mmol/L） of DCA was determined at indicated times （2 h and 4 h ） based on the MTS assay. Action of DCA on cell viability, membrane integrity was assessed by neutral red uptake （NRU） assay and lactate dehydrogenase （LDH） release test and measurement of superoxide dismutase （SOD） activity. Fluores- cence quantitative reverse transcription polymerase chain reaction （FQ- RT- PCR） was employed for detection and quantization of the chemokine receptor CXCR2 and chemokine receptor CXCR3 mRNA in peripheral blood lymphocyte treated with different concentrations of DCA. Results DCA had a more vital effect on peripheral blood lymphocyte than TCE and TCA. A concentration- dependent release of LDH was observed at 4 h after cells were exposed to different doses of DCA （0.88,1.75, 3.50 and 7.00 mmol/L） （P〈O.05）, and DCA also caused an inhibition of SOD activity in a concentration- dependent manner （P〈O.05）. The results ofFQ- RT- PCR indicated that CXCR2 and CXCR3 mRNA were all over- expression. At 48 h after the DCA of 0.5 mmol/L and 10.00 mmol/L was used, CXCR2 and CXCR3 mRNA were 10.34, 5.66- fold and 19.43, 8.75- fold of those in the control group （P〈 0.01 ）. Conclusion DCA is of a great cytotoxicity and may be one of crucial evocators on DMLT.