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目的:分析幼年特发性炎症性肌病(JIIM)患儿肌炎特异性抗体(MSAs)及肌炎相关性抗体(MAAs)与临床亚型的相关性，探讨MSAs在JIIM中的意义。方法:回顾性分析2017年1月至2019年10月在南京医科大学附属儿童医院风湿免疫科住院的JIIM患儿53例，采用欧蒙免疫印迹法检测血清16项肌炎抗体(MSAs和MAAs)的阳性率，分析肌炎抗体与JIIM患儿临床表现、并发症、治疗及预后的相关性。其中MSAs包括抗染色体-解旋酶-DNA结合蛋白(Mi-2)α抗体、抗Mi-2β抗体、抗转录中介因子(TIF)1-γ抗体、抗黑色素瘤分化相关基因5(MDA5)抗体、抗核基质蛋白2(NXP2)抗体、抗小泛素样修饰物活化酶抗体、抗信号识别颗粒抗体和抗合成酶(ARS)抗体。结果:53例JIIM患儿肌炎抗体(MSAs和MAAs)阳性率为69.8%(37/53例)，MSAs阳性率为66.0%(35/53例)，最常见MSAs为抗NXP2抗体(10例)，其次为抗TIF1-γ抗体(9例)、抗MDA5抗体(7例)、抗ARS抗体(7例)。抗NXP2抗体阳性患儿以中度肌肉损害(7例)和中度皮肤损害(7例)为主，抗TIF1-γ抗体阳性患儿5例出现持续性皮疹，抗MDA5抗体阳性患儿有严重皮疹(2例)和肺间质病变(5例)。与抗NXP2抗体阴性患儿比较，抗NXP2抗体阳性患儿的天冬氨酸转氨酶(AST)及肌酸激酶(CK)水平明显升高，抗TIF1-γ抗体、抗MDA5抗体和抗ARS抗体阳性患儿的CK水平均明显降低，抗MDA5抗体阳性患儿的血清铁蛋白水平明显升高，差异均有统计学意义(均n P<0.05)。抗NXP2抗体与皮疹(n r＝0.360，n P＝0.008)和吞咽困难(n r＝0.504，n P<0.001)呈正相关。抗MDA5抗体(n r＝0.497，n P<0.001)和抗ARS抗体(n r＝0.621，n P<0.001)与肺间质病变呈正相关。抗TIF1-γ抗体(n r＝-0.542，n P<0.001)和抗MDA5抗体(n r＝-0.446，n P<0.001)与CK水平呈负相关。n 结论:MSAs在JIIM患儿中阳性率较高，部分MSAs与JIIM特征性临床表型相关。MSAs可为JIIM患儿的临床亚类分型和疗效针对性评价提供指导。“,”Objective:To explore the clinical values of myositis specific antibodies (MSAs) in juvenile idiopathic inflammatory myopathies (JIIM) by analyzing the correlation between clinical subtypes and myositis autoantibo-dies, including MSAs and myositis related antibodies (MAAs) in a cohort of patients with JIIM.Methods:A total of 53 JIIM children were hospitalized in the Department of Rheumatology and Immunology, Children′s Hospital of Nanjing Medical University from January 2017 to October 2019 and were retrospectively analyzed.The serum concentrations of MSAs and MAAs were measured by Euroline Autoimmune Inflammatory Myopathies 16 Ag kit.The correlation among myositis antibody and clinical manifestations, complications, treatment, and prognosis in JIIM children was analyzed.MSAs include autoantibodies against Mi-2 α and Mi-2β autoantigens, transcription intermediary factor 1 gamma (TIF1-γ), melanoma differentiation-associated protein 5 (MDA5), nuclear matrix protein 2 (NXP2), small ubi-quitin-like modifier activating enzyme, signal recognition particle, and aminoacyl-transfer RNA synthetase (ARS).Results:The positive rates of MSAs and MAAs were 69.8% (37/53 cases) and 66.0% (35/53 cases), respectively.The most common MSAs were anti-NXP2 (10 cases), followed by anti-TIF1-γ (9 cases), anti-MDA5 (7 cases) and anti-ARS (7 cases). Moderate muscle damage (7 cases) and moderate skin damage (7 cases) were the main manifestations of anti-NXP2 antibody positive children.Persistent rash occurred in 5 children with positive anti-TIF1-γ antibody.The children with positive anti-MDA5 antibody developed severe skin rash (2 cases) and interstitial lung disease (5 cases). Compared with the children with negative anti NXP2 antibody, the levels of aspartate transaminase(AST)and creatine kinase (CK) in the children with positive anti NXP2 antibody significantly increased, the CK levels of anti TIF1-γ antibody, anti MDA5 antibody and anti ARS antibody obviously decreased, and the serum ferritin level of anti MDA5 antibody positive children greatly increased, while the differences were statistically significant (alln P<0.05). Anti-NXP2 antibody was positively correlated with rash (n r=0.360, n P=0.008) and dysphagia (n r=0.504, n P<0.001). Anti-MDA5 antibody (n r=0.497, n P<0.001) and anti-ARS antibody (n r=0.621, n P<0.001) were positively associated with interstitial lung disease.Anti-TIF1-γ antibody (n r=-0.542, n P<0.001) and anti-MDA5 antibody (n r=-0.446, n P<0.001) were negatively related to CK level.n Conclusions:JIIM patients have high frequencies of MSAs.Several MSAs are specifically associated with characteristic clinical phenotypes, which has implications for diagnosis and a more personalized approach to therapy.