中文摘要：

无菌抽取犬外周血，分离单核细胞，经PHA刺激后收集细胞，使用Trizol提取细胞总RNA；利用自行设计的引物．反转录合成eDNA第1条链，PCR扩增出长约441bp的白细胞介素．21（IL-21）基因带。经纯化回收．将基因克隆至pMD18-T，筛选阳性克隆测序证明扩增的eDNA的序列与己报道的序列相一致。

英文摘要：

In this study, canine interleukin-21 cDNA was amplified. Canine leukocytes were separated from ,peripheral blood stimulated with PHA for 12 - 24 h. Total RNA was extracted from PHA-aetivated canine T cells by using Trizol. The full length eDNA of canine IL-21 gene was amplified by RT-PCR using leukocyte mRNA as a template and designed primer, which was proven to be about 441bp through agarose gel eleetrophoresis. Then IL-21 eDNA was cloned into pMD18-T. Sequencing result showed that the full length eDNA was 441bp, which was identical with that published. Target gene was successfully amplified by RT-PCR and was proven by sequencing.