The Intervention Effects Of Glucocorticiod On The Immune Function Of Children With Myasthenia Gravis

ObjectivesTo explore the immunologic pathogenesis of myasthenia gravis in children and the intervention effects of glucocorticoid on its immune function.MethodsForty cases of myasthenia gravis children from the outpatient department of neurology specialist at Children's Hospital of Chongqing Medical University from March 2007 to September 2007 was the observation group, and 20 cases of healthy children from children healthcare department in the same period as the normal control group. After the myasthenia gravis children were accepted glucocorticoid prednisone therapy, they were extracted the peripheral blood for detecting and comparing the alteration of immune function of observation group pre- and post-glucocorticoid prednisone therapy. The serum levels of IgG, IgM, IgA, C₃, C₄ and IgG subclasses (IgG₁, IgG₂, IgG₃, IgG₄) were measured by scattering immunoturbidimetric method; T cell subsets of CD₃⁺, CD₄⁺, CD₈⁺ and CD₄⁺ /CD₈⁺ were measured by using flow cytometry; AChR-Ab and cytokines INF-γ, TGF-β₁, IL-10, IL-18 were detected by ELISA.Results1. The positive rate of AChR-Ab was low(42.5%)in myasthenia gravis children. The serum levels of total IgG, IgM, IgA and C4, IgG2, IgG4 were no statistical significance between the observation group and the normal control group(t=0.05～1.50, P>0.05). The serum levels of IgG1, IgG3 and C3 were higher in the observation group than in the normal control group and the differences were statistically significant (t=2.66～3.68, P<0.05). After 3-month treatment with glucocorticoid, the positive rate of AChR-Ab was decreased(22.5%)than pre-treatment(42.5%), but the difference was no statistical significance(x²=3.65, P>0.05), the serum level of IgG1 was decreased than pre-treatment and the difference was statistically significant (t=3.30, P<0.01).2. There was no significant difference of the percentage of CD₃⁺ T cells between the observation group and the normal control group(t=1.36, P>0.05). The percentage of CD₄⁺ T cells and the ratio of CD₄⁺/CD₈⁺ were higher, the percentage of CD₈⁺ T cells was lower in the observation group than in the normal control group, and the differences were statistically significant (t=2.85～4.23, P<0.01). After 3-month treatment with glucocorticoid, the percentage of CD₄⁺ T cells and the ratio of CD₄⁺/CD₈⁺ were decreased and the percentage of CD₈⁺ T cells was increased than pre-treatment, the differences were statistically significant (t=3.40～8.23, P <0.01).3. The serum levels of cytokine INF-γand IL-18 were higher and IL-10 and TGF-β₁ were lower in the observation group than in the normal control group, the differences were statistically significant (t=4.45～16.72, P<0.01). After 3-month treatment with glucocorticoid, the serum levels of INF-γand IL-18 were decreased and the sera levels of TGF-β₁ were increased than pre-treatment, the differences were statistically significant (t=8.12～10.68, P<0.01). There was no significant alterations of the serum level of IL-10 between pre- and post-treatment(t=0.26, P> 0.05).Conclusions1. The factors of the humoral immune disorder, T-cell subsets imbalance and cytokine network imbalance are extensively involved in the pathogenesis of myasthenia gravis in children, and the cellular immune disorder is the main factor.2. Glucocorticoid could regulate the function of humoral immunity in myasthenia gravis children by inhibiting the production of AChR-Ab subset IgG1.3. Glucocorticoid could resume a normal Th/Ts balance by redistributing the T-lymphocyte subsets of myasthenia gravis children and suppress the overload cellular immune response.4. Glucocorticoid could adjust the abnormal immune response process of myasthenia gravis children by regulating the secretion of cytokines IFN-γ, TGF-β₁ and IL-18, which would ultimately inhibit the formation of autoantibodies.