目的　分离和鉴定刺激人肺腺上皮细胞 (SPC A 1) β 防御素 1(hBD 1)基因表达的卡介苗胞壁活性蛋白 ,开发增强粘膜抗菌肽基因表达的免疫增强剂为防治粘膜感染的研究打基础。方法　采用超声破碎细胞、蔗糖密度梯度离心、SephadexG 15 0柱层析等方法分离卡介苗胞壁蛋白质组分 ;应用逆转录聚合酶链反应 (RT PCR)法和Northern杂交检测SPC A 1细胞hBD 1mRNA的表达 ;采用琼脂糖弥散杀菌法检测SPC A 1细胞培养上清的抗菌活性。结果　利用RT PCR和Northern杂交分析 ,证实卡介苗刺激SPC A 1细胞hBD 1mRNA的表达增强了 2倍。卡介苗胞壁蛋白SephadexG 15 0层析所得 6个组分中 ,组分 5 [相对分子质量 (Mr)范围在 2 1× 10 3～ 2 9× 10 3]诱导SPC A 1细胞hBD 1mRNA的表达增强 4倍 ,其培养上清的抗菌活性显著增强。这种诱导作用具剂量和时间依赖关系。结论　卡介苗能增强人肺腺上皮SPC A 1细胞hBD 1mRNA的表达及其抗菌活性 ;Mr 为 2 1× 10 3～ 2 9×10 3 的胞壁蛋白组分起这种刺激作用 OBJECTIVE To isolate and identify BCG cell wall active proteins that stimulate the expression of β-defensin 1 (hBD 1) in human lung epithelial cells (SPC A 1) and to develop immunostimulants that enhance the expression of mucosal antimicrobial peptide genes for the prevention and treatment of mucosal infections basis. Methods The protein components of the cell wall of BCG were isolated by sonication, sucrose density gradient centrifugation and Sephadex G-150 column chromatography. The hBD-1 mRNA of SPC A 1 cells was detected by reverse transcriptase-polymerase chain reaction (RT PCR) and Northern blotting The antibacterial activity of SPC A 1 cell culture supernatant was detected by agarose diffusion bactericidal assay. Results RT PCR and Northern blot analysis confirmed that BCG-stimulated SPC A 1 cells hBD 1 mRNA increased 2-fold. Among the 6 fractions obtained from the BCG cell wall protein SephadexG 15 0, the expression of hBD 1 mRNA in SPC A 1 cells was enhanced by fraction 5 [relative molecular mass (Mr) ranged from 2 × 10 3 to 2 × 10 3] 4 times, the culture supernatant antibacterial activity was significantly enhanced. This induction has a dose and time-dependent relationship. Conclusion Bacillus Calmette-Guérin can enhance the expression of hBD 1 mRNA in human lung epithelial SPC A 1 cells and its antibacterial activity. The cell wall proteins with Mr 2 1 × 10 3 -2 9 × 10 3 play the role of stimulus