目的：为了在大肠杆菌中高效表达ｈＩＬ３ｃＤＮＡ，获得ｈＩＬ３蛋白，拟对天然型ｈＩＬ３进行构建以获得新的突变体，同时进行了活性测定，以便深入了解ｈＩＬ３的结构与功能之间的关系。方法：利用ＰＣＲ技术对天然型ｈＩＬ３Ｎ末端第３位蛋氨酸（Ｍｅｔ３）和Ｃ末端第１７位蛋氨酸（Ｌｙｓ１１６）进行定点突变，获得突变体ＭｈＩＬ３和ＭＶｈＩＬ３。结果：经Ｓｕｇｅｒ双脱氧法测序证实突变体ＭｈＩＬ３ｃＤＮＡ，ＭＶｈＩＬ３ｃＤＮＡ的活性为６．９×１０４Ｕ／ｍｌ，而天然型的是１．５×１０４Ｕ／ｍｌ。天然型ｐＳＭ５３ｈＮＩＬ３表达量占菌体总蛋白的７％，突变型ｐＳＭ５３ＭＶｈＩＬ３表达量占菌体总蛋白的１６％。结论：人ＩＬ３ｃＤＮＡ可通过ＰＣＲ技术进行定点突变，所获得的突变型ｐＳＭ５３ＭＶｈＩＬ３活性比天然型ｐＳＭ５３ｈＩＬ３高３～４倍 Objective: In order to efficiently express hIL 3 cDNA in E. coli to obtain hIL 3 protein, hIL 3 was proposed to construct a natural mutant to obtain new, at the same time the activity determination in order to better understand the structure of hIL 3 and The relationship between functions. Methods: The methylation of methionine (Met3) and methionine (Lys116) at the 3’-end of the native hIL 3 gene was detected by PCR, and the mutants MhIL3 and MVhIL3 were obtained. Results: Suger dideoxy sequencing confirmed the mutant MhIL 3 cDNA, MVhIL 3 cDNA activity of 6.9 × 104U / ml, while the natural type is 1.5 × 104U / ml. Natural pSM53hNIL  3 expression accounted for 7% of the total bacterial protein, mutant pSM53MVhIL  3 expression of total bacterial protein 16%. Conclusion: Human IL  3cDNA can be site-directed mutagenesis by PCR technology, obtained mutant pSM53MVhIL  3 activity than natural pSM53hIL  3 3 to 4 times