本研究通过体外细胞实验观察多发性骨髓瘤(MM)患者尿中本周氏蛋白(Bence Jones protein,BJP)酰胺酶催化作用与肾小管细胞毒性作用的关系,进一步了解BJP对MM肾损伤的毒性机制。测定13例MM患者尿BJP的酰胺酶动力学参数米氏常数(Km)和催化常数(kcat);以不同浓度BJP与猪肾小管上皮细胞(LLC-PK1)共同培养24 h后,用MTT法测定细胞增殖抑制率;以明显抑制细胞增殖的BJP浓度与LLC-PK1细胞共同培养后使用流式细胞术检测细胞凋亡。结果表明,临床出现肾损伤的MM患者尿中BJP较未出现肾损伤MM患者尿中BJP更易对LLC-PK1细胞产生毒性作用,且BJP的kcat值越高,对LLC-PK1细胞毒性作用越强。流式细胞仪检测发现,BJP能够诱导LLC-PK1细胞发生凋亡及坏死,毒性作用随BJP浓度的增高而增强。结论:BJP能够对肾小管上皮细胞产生直接毒性作用,并随BJP浓度的增高而增强;BJP酰胺酶催化作用强度与其毒性作用呈正相关,其可能是MM患者发生肾损伤的机制之一。 In this study, we observed the relationship between urinary Benzy Jones protein (BJP) amidase activity and renal tubular cytotoxicity in vitro by cell experiment to further understand the toxic effects of BJP on MM kidney injury mechanism. The kinetic parameters of amidase (Km) and catalytic constant (kcat) of urinary BJP in urine of 13 patients with MM were measured. After cultured with different concentrations of BJP and porcine renal tubular epithelial cells (LLC-PK1) for 24 h, The inhibitory rate of cell proliferation was determined. Apoptosis was detected by flow cytometry after co-cultured with LLC-PK1 cells at the concentration of BJP significantly inhibited cell proliferation. The results showed that BJP in urine of patients with clinical kidney injury was more likely to cause toxic effects on LLC-PK1 cells than urine of BJP without renal injury, and the higher the kcat value of BJP, the stronger the cytotoxic effect on LLC-PK1 cells . Flow cytometry showed that BJP could induce apoptosis and necrosis in LLC-PK1 cells. The toxic effect of BJP increased with the increase of BJP concentration. CONCLUSION: BJP can induce direct toxicity to renal tubular epithelial cells and increase with the increase of BJP concentration. BJP amidase catalytic activity is positively correlated with its toxicity, which may be one of the mechanisms of renal injury in MM patients.