目的：重症肌无力（myasthenia gravis，MG）是一种自身免疫性疾病，发病机制自今仍未完全清楚。在其他自身免疫性疾病研究中发现热休克蛋白90（heat shock protein 90，HSP90）表达有异常，该研究探讨MG儿童外周血单个核细胞（PBMC） 中HSP90亚型mRNA表达水平和血清皮质醇的水平，以了解机体的应激状态。方法：对新发MG患儿36例及健康儿童19例（作为对照组）留取新鲜血液，取其上清液用化学发光法测定血清皮质醇水平；从其血细胞中分离出PBMC，采用RT-PCR方法检测HSP90α和HSP90β亚型mRNA。结果：MG患儿HSP90α（0.7329±0.2120）、HSP90β（0.7193±0.2869）mRNA表达水平比对照组（分别为0.5574±0.2084，0.4892±0.2104）明显升高（P<0.01）；MG患儿血清皮质醇（285.04±146.39 nmol/L）水平比对照组（196.25±64.52 nmol/L）升高（P<0.05）。结论：HSP90α和HSP90β mRNA 表达水平升高可能与MG疾病本身有关；而血清皮质醇水平升高表明机体处于高应激状态或可能与患儿糖皮质激素受体异常有关。［中国当代儿科杂志，2009，11（6）：453-456］

OBJECTIVE: Myasthenia gravis is an autoimmunity disease and its pathogenesis has not been fully identified. Heat shock protein 90 (HSP90) shows an abnormal expression in other autoimmunity diseases. This study examined the mRNA expression of two isoforms of HSP90 in peripheral blood mononuclear cells (PBMC) and serum cortisol content in children with myasthenia gravis. METHODS: Thirty-six children with myasthenia gravis and 19 healthy children were enrolled. Serum cortisol content was measured by the chemiluminescence assay. The expression of HSP90α and HSP90β mRNA in PBMC was detected by the RT-PCR technique. RESULTS: The mRNA expression of HSP90α (0.7329±0.2120) and HSP90β (0.7193±0.2869) in children with myasthenia gravis was significantly higher than that in healthy controls (0.5574±0.2084 and 0.4892±0.2104 respectively) (P<0.01). Serum cortisol content (285.04±146.39 nmol/L) in children with myasthenia gravis was also higher than that in the healthy controls (196.25±64.52 nmol/L) (P<0.01). CONCLUSIONS: The high mRNA expression of HSP90α and HSP90β in PBMC might be associated with the development of myasthenia gravis. The high serum cortisol level indicates a high stress state or might be correlated to the glucocorticoid receptor abnormality in children with myasthenia gravis.［Chin J Contemp Pediatr, 2009, 11 (6):453-456］