目的:探究百日咳患儿的血清百日咳毒素(pertussis toxin，PT)-IgG抗体水平及其影响因素。方法:收集2015年7月至2018年12月深圳市儿童医院实验室确诊为百日咳且完成PT-IgG抗体检测的患儿的年龄、病程、疫苗接种状况等临床资料，采集患儿静脉血检测PT-IgG抗体水平，采集鼻咽拭子进行聚合酶链反应(polymerase chain reaction，PCR)检测百日咳鲍特菌核酸，并进行百日咳鲍特菌培养。两组间比较采用曼-惠特尼n U检验，多组间比较采用Kruskal-Wallis检验。采用多元线性回归分析PT-IgG抗体水平的影响因素。n 结果:共纳入871例百日咳患儿，年龄为4(2, 7)个月，年龄4~8周、>8周组患儿PT-IgG抗体水平分别为0(0, 7.9) IU/mL、8.7(0, 56.0) IU/mL、26.6(5.1, 82.9) IU/mL和68.0(15.3, 118.8) IU/mL，不同年龄和病程组患儿PT-IgG抗体水平差异均有统计学意义(n H＝88.346、94.076，均n P<0.01)。疫苗未接种、已接种至少1剂者PT-IgG抗体水平分别为0.9(0, 12.7) IU/mL、14.6(0, 86.3) IU/mL，差异有统计学意义(n Z＝-8.520，n P2周的患儿中6例为PT-IgG≥80 IU/mL。年龄、病程、疫苗接种状态是PT-IgG抗体水平的独立影响因素(n β＝0.108、0.189、0.250，均n P<0.01)。n 结论:百日咳患儿的PT-IgG抗体水平受年龄、病程、疫苗接种状态影响，单份血清以80 IU/mL为诊断界值可能导致漏诊率增加，需进一步探索适合我国儿童的标准。“,”Objective:To investigate the levels and influencing factors of serum pertussis toxin (PT)-IgG antibody in children with pertussis.Methods:The clinical data including age, course of disease and vaccination status of children with laboratory-confirmed pertussis and tested for PT-IgG antibody in Shenzhen Children′s Hospital from July 2015 to December 2018 were collected. Venous blood samples were obtained to detect PT-IgG antibody levels. Nasopharyngeal swabs were taken for polymerase chain reaction (PCR) test to detect n Bordetella pertussis nucleic acid and culture of n Bordetella pertussis. Mann-Whitney n U test was used for comparison between two groups.Kruskal-Wallis test was used for comparison among multiple groups. Multiple linear regression was used to analyze the influencing factors of PT-IgG antibody levels.n Results:A total of 871 children aged 4(2, 7) months were included, among whom, 592(68.0%) cases were under six months and 754 (86.6%) cases were under one year old. The course of disease was 15 (11, 20) days. Among 871 cases, 864 (99.2%) cases were PCR test and (or) culture positive, including 696 cases positive only for PCR test, 35 cases positive only for culture and 133 cases positive for both PCR test and culture. There were 452 (51.9%) children who were not vaccinated and 346 (39.7%) children vaccinated with at least one dose. In terms of age, the PT-IgG amtibody levels of children aged 0 to two months, three to five months, six months to two years and ≥three years were 0.7 (0, 8.2) IU/mL, 2.3 (0, 23.0) IU/mL, 24.6 (0, 112.3) IU/mL and 24.9 (0, 114.7) IU/mL, respectively. The PT-IgG antibody levels of children after onset of symptoms at 0 to two weeks, more than two to four weeks, more than four to eight weeks and more than eight weeks were 0(0, 7.9) IU/mL, 8.7(0, 56.0) IU/mL, 26.6(5.1, 82.9) IU/mL and 68.0(15.3, 118.8) IU/mL, respectively. The differences were both statistically significant (n H=88.346 and 94.076, respectively, both n P<0.01). The PT-IgG antibody levels in children who were unvaccinated and vaccinated with at least one dose were 0.9 (0, 12.7) IU/mL and 14.6(0, 86.3) IU/mL, respectively. The difference was statistically significant (n Z=-8.520, n Ptwo weeks, among whom, six patients had PT-IgG≥80 IU/mL. Age, course of disease and vaccination status were independent influencing factors of PT-IgG levels (n β=0.108, 0.189 and 0.250, respectively, all n P<0.01).n Conclusions:The levels of PT-IgG antibody in children with pertussis are influenced by age, course of disease and vaccination status. The single serum PT-IgG of 80 IU/mL as cut-off value in the diagnosis of pertussis may lead to a increase of missed diagnosis. Therefore, it is necessary to further explore the standards suitable for children in China.