目的　考察经免疫亲和层析纯化的马破伤风免疫球蛋白F（ab'）₂的等电点分布与比活性的关系，为工艺优化建立更好的质量表征。方法　采用毛细管等电聚焦电泳测定免疫亲和层析纯化前后马破伤风免疫球蛋白F（ab'）₂的等电点，并进行统计分析。结果　免疫亲和层析纯化前后样品的等电点分布范围均在4.97~9.88之间；纯化后样品等电点的分布更为集中；样品纯化后在等电点区间6.01—7.00和8.01—9.00的峰面积占比较纯化前的有所增加，平均增加幅度分别为70%、37%；在等电点区间7.01—8.00和9.01—10.00的峰面积占比降低，平均降低幅度分别为25%、26%。结论　根据研究结果推测，马破伤风免疫球蛋白F（ab'）₂中针对破伤风毒素的中和活性较强的抗体等电点可能主要分布在6.01—7.00和8.01—9.00。

Objective　To investigate the relationship between specific activity and isoelectric point distribution of equine tetanus immunoglobulin F（ab'）₂, so as to establish a better quality characterization for optimizing the process.Methods　The isoelectric points of equine tetanus immunoglobulin F（ab'）₂ before and after immunoaffinity chromatography purification were measured by capillary isoelectric focusing（CIEF） electrophoresis, and the experimental results were statistically analyzed.Results　The isoelectric point distribution ranges of the samples before and after purification by immunoaffinity chromatography were both 4.97-9.88. The isoelectric point distribution of the purified samples was more concentrated. After purification, the propartions of peak area in the isoelectric point ranges of 6.01-7.00 and 8.01-9.00 increased compared with those before purification, with an average increase of 70% and 37%, respectively. In the isoelectric point ranges of 7.01-8.00 and 9.01-10.00, the peak area proportion decreased by 25% and 26%, respectively.Conclusion　According to the results of this study, it is speculated that the isoelectric points of the antibody with strong neutralizing activity against tetanus toxin in equine tetanus immunoglobulin F(ab')₂ may mainly be distributed in the ranges of 6.01-7.00 and 8.01-9.00.