脐血乙型肝炎病毒血清学标记物诊断宫内感染的局限性

Limitation of hepatitis B markers in cord blood for diagnosing intrauterine infection of hepatitis B virus

目的探讨脐血乙型肝炎病毒（hepatitisBvirus，HBV）血清学标记物在诊断HBV宫内感染中的应用价值。方法2011年10月8日至2013年5月31日，在南京大学医学院附属鼓楼医院、江苏省泰兴市人民医院和镇江市妇幼保健院分娩的孕妇中，纳入278例乙型肝炎表面抗原（hepatitisBsurfaceantigen，HBsAg）阳性、妊娠期未接受抗病毒治疗、无丙型肝炎病毒或人类免疫缺陷病毒感染的孕妇（其中3例双胎）。281例新生儿生后12h内均进行被动免疫及主动免疫。孕妇分娩后立即采集脐血，分娩后2d内采集外周血，婴儿7～12月龄随访时采集外周血。采用荧光定量聚合酶链反应技术检测血清HBVDNA，检测下限为10^2U／ml。采用酶联免疫吸附试验定性检测HBsAg、乙型肝炎表面抗体（hepatitis Bsurfaceantibody，抗HBs）、乙型肝炎e抗原（hepatitis Beantigen，HBeAg）、乙型肝炎e抗体（hepatitis Beantibody，抗HBe）和乙型肝炎核心抗体（hepatitisBcoreantibody，抗-HBc），以及抗HBcIgM。分析7-12月龄时的婴儿随访率，母血、脐血及婴儿的HBV血清标记物水平，婴儿慢性HBV感染率，以及脐血HBVDNA、抗-HBcIgM水平与HBV宫内感染的关系。结果7～12月龄时婴儿随访率为76．2％（214／281）。71例HBeAg阴性孕妇分娩新生儿71例，其中8例（11．3％，8／71）脐血HBVDNA阳性；随访到56例，其中7例（12．5％，7／56）脐血HBVDNA阳性，但7～12月龄时，54例（96．4％，54／56）抗-HBs阳性，HBsAg和抗-HBc均为阴性，无一例HBV感染。207例HBeAg阳性孕妇分娩新生儿210例，其中86例（41．0％，86／210）HBVDNA阳性；随访到158例，其中38例（24．1％，38／158）脐血HBVDNA和HBsAg同时阳性；但7～12月龄时仅6例（3-8％，6／158）HBsAg、HBeAg和抗-HBc同时阳性，HBVDNA为1．55×1071．51×10^9U／ml，诊断慢性HBV感染。脐血HBVDNA≥10^5U／ml者中随访到7例，其中4例7～12月龄时未感染且有保护力；3例确诊HBV感染。另外3例HBV感染婴儿的脐血HBVDNA，1例为9．18×10^3U／ml，2例低于检测下限。281例脐血标本的抗-HBcIgM均阴性。结论脐IfILHBVDNA阳性不能诊断HBV宫内感染，HBVDNA阴性不能排除HBV母婴传播；脐血抗HBcIgM阳性率极低，阴性不能排除HBV宫内感染。

Objective To investigate the role of hepatitis B virus （HBV） DNA and hepatitis B core antibody （anti HBc） IgM in cord blood for diagnosis of HBV intrauterine infection. Methods FromOctober 8, 2011 to May 31, 2013, a total of 278 pregnant women with positive hepatitis B surface antigen （HBsAg） were enrolled from Nanjing Drum Tower Hospital, Taixing People＇s Hospital, and Zhenjiang Metarnal and Child Hospital. None of them had received antiviral therapy, co infection with hepatitis C virus or human immunodeficiency virus. All 281 newborns （three pairs of twins） of them had been vaccinated against hepatitis B and received hepatitis B immunoglobulin （HBIG） within 12 h after birth. Serum samples of HBsAg-positive women at 2 days after delivery and cord sera of their neonates as well as sera of these children followed up at the age of 7-12 months were collected. HBV DNA levels were detected by fluorescent quantitative polymerase chain reaction, with the lower detection limit of 102 U/ml. HBV serologic markers and anti-HBc IgM were examined by enzyme linked immunosorbent assay. HBsAg and hepatitis B e antigen （HBeAg） were quantified with Abbott reagents. Then we analyzed the rate of infants followed-up, the level of HBV markers, and the relationship of HBV DNA, anti HBc IgM and HBV intrauterine infection. Results Totally 214 （76.2%） infants were followed up at the age of 7-12 months. Of the 71 cord blood samples of HBeAg-negative mothers, eight （11.3%） had detectable HBV DNA; among the 56 followed-up infants, seven （9.9%） were positive for HBV DNA, while 54 were positive for anti-HBs and negative for both HBsAg and anti-HBc. None of the above 56 infants were positive for HBsAg, HBeAg, or anti-HBc. Of the 210 cord blood samples of the 207 HBeAg-positive mothers, 86 （41.0%） had detectable HBV DNA. Of the 158 infants who attended the follow-up, 38 （24.1%, 38/158） were positive for both HBV DNA and HBsAg, while only six （3.8%, 6/158） were positive for HBsAg, HBeAg, and anti-HBc. Chronic HBV infection was diagnosed when levels of HBV DNA ranged from 1.55× 10^7 to 1.51 × 10^9 U/ml. Seven infants with HBV DNA ≥ 10^5 U/ml in cord blood were followed up, and only three confirmed to be HBV infection. The other four cases were not infected and effectively protected. Of the three infected infants, one showed 9.18 × 10^3 U/ml HBV DNA level in cord blood, and the remaining two were below 10^2 U/ml. Anti- HBc IgM was negative in all 281 cord blood. Conclusions The intrauterine infection can not be determined by high level of HBV DNA in cord blood, nor be ruled out by undetectability of HBV DNA. The positive rate of anti-HBc IgM in cord blood is extremely low, indicating the useless of anti-HBc IgM in cord blood to define intrauterine infection.