目的：探讨植物血凝素(PHA)、白细胞介素-2(IL-2)、抗CD3单克隆抗体(αCD3Ab)激活的脐血单个核细胞(CBMC)体外对K562的杀伤活性，以及外源性刺激因子对CBMC的可溶性白细胞介素-2受体(sIL-2R)含量的影响。方法：采集CBMC分别与不同刺激因子体外短期培养，台盼蓝拒染法测效应细胞的增殖能力，ELISA法检测上清液中sIL-2R的含量， 3 H-TdR释放法测定效应细胞体外对K562靶细胞的杀伤活性。结果：脐血PHA-CD3AK细胞在体外培养3 d后增殖倍数、活化后上清液中sIL-2R的含量显著高于PHA-LAK，CD3AK和LAK细胞(P<0.05)。PHA-CD3AK细胞体外对白血病细胞株K562细胞的细胞毒活性明显高于PHA-LAK，CD3AK和LAK细胞(P<0.05)。结论：脐血单个核细胞经PHA，IL-2和αCD3Ab激活后，可有效形成PHA-CD3AK效应细胞，其增殖活性、细胞毒性均高于PHA-LAK，CD3AK和LAK细胞。

OBJECTIVE: To explore the cytotoxicity to K562 cells and the solube interleukin 2 receptor (sIL 2R) level of cord blood, cord blood mononuclear cells (CBMC) activated by phytohemagglutinin (PHA), αCD3Ab and IL 2 in vitro. METHODS: By calculating the number of living cells in different culture medium systems, the proliferative capability of activated CBMC was measured. The level of sIL 2R in the supernatant of the cultured CBMC was measured using ELISA. Tumor cells necrosis induced by the effecter cells was detected by the release of 3H TdR. RESULTS: After a 3 day culture in vitro, the proliferation, cytotoxicity and the level of sIL 2R in cord blood PHA CD3AK cells were much greater than those in PHA LAK,CD3AK and LAK cells (P< 0.05 ). CONCLUSIONS: The results show that the synergistic enhancing role of PHA,IL 2 and αCD 3Ab in CBMC activation and PHA CD3AK cells have some advantages over PHA LAK, CD3AK and LAK cells in the proliferation and cytotoxicity.