Clinical Study On AchR-Ab, Titin-Ab And Foxp3~+CD4~+CD25~+ Treg In Myasthenia Gravis Patients

Objective:To explore the further pathogenesis of Myasthenia Gravis(MG) and provide the theory of a new potential therapy method to MG or other autoimmune diseases,the correlation between the level of AchR-Ab, Titin-Ab in peripheral blood and the expression of Foxp3~+CD4~+CD25~+T regulatory cells(Foxp3~+CD4~+CD25~+Treg) in peripheral blood of MG were analyzed.Methods:1. 50 patients with MG, as well as 21 cases non-MG with other neurological diseases (OND) and 30 health control (HC) were collected, from August 2007 to January 2009, in the first affiliated hospital of Soochow University. According to Osserman classification, all MG patients were divided into Ocular MG group and generalized MG group. And according to pathological histology, all MG patients were divided into MG with thymoma (MGT) group and non-thymoma MG (NTMG) group.2. Using ELISA, we tested the level of AchR-Ab and Titin-Ab in the sera and studied the relationship between two kinds of antibodies and severity of muscle weakness.3. Using FCM, we tested the frequency of CD4~+CD25~+Treg and the expression of Foxp3 in CD4~+ CD25~+Treg in the peripheral blood of 22 patients with MG and 20 health control (HC) and studied the relationship between the expression of Foxp3 and severity of muscle weakness. Results:1. ELISA:(1) The level of AchR-Ab and Titin-Ab and the positive rate of AchR-Ab and Titin-Ab in MG were significantly higher than those of OND group and HC group (P<0.01); (2) The level of AchR-Ab was no significantly different in generalized MG as compared to Ocular MG(P>0.05), but the positive rate of AchR-Ab in generalized MG was significantly higher than Ocular MG (P<0.05). And the positive rate and the level of Titin-Ab in Ocular MG were significantly lower than generalized MG (P<0.01); (3) The level of AchR-Ab and Titin-Ab and the positive rate of AchR-Ab and Titin-Ab were significantly increased in MGT as compared to NTMG(P<0.01); (4) There was positive correlation between the level of Titin-Ab and severity of muscle weakness(r=0.746, P<0.01), but no correlation between the level of AchR-Ab and severity of muscle weakness(r=0.241, P>0.05); (5) Comparing with CT scan of thymus in diagnosis of MGT, Titin-Ab was lower in sensitivity, but higher in specificity(P<0.01).2. FCM: (1)There were no significant differences of the percentage of CD4~+CD25~+Treg cells in peripheral blood between MG group and HC group(P>0.05), but the expression of Foxp3 in CD4~+ CD25~+Treg in peripheral blood in MG group was significantly decreased as compared to HC group(P<0.01); (2) There were no significant differences of the expression of Foxp3 in CD4~+CD25~+Treg in peripheral blood, in MG patients, between male and female , and were no significant differences between thymectomized MG patients and non-thymectomized MG patients; (3) The expression of Foxp3 in CD4~+CD25~+Treg in peripheral blood in generalized MG were significantly lower than Ocular MG (P<0.01); (4) There was negative correlation between the expression of Foxp3 in CD4~+CD25~+Treg in peripheral blood and severity of muscle weakness(r=-0.873, P<0.01); (5) There was negative correlation between the expression of Foxp3 in CD4~+CD25~+Treg in peripheral blood and the level of AchR-Ab and Titin-Ab(r=-0.449 and -0.691; P<0.05, P<0.01). Conclusion:1. Serum AchR-Ab and Titin-Ab test are helpful in diagnosis of MG, especially to MGT with Titin-Ab. In diagnosing MGT, Titin-Ab has higher specificity than CT scan, and the deficient of CT scan can be solved by assaying Titin-Ab.2. There are positive correlation between the level of Titin-Ab and severity of muscle weakness, but no correlation between the level of AchR-Ab and severity of muscle weakness. Therefore it is indicated that Titin-Ab test is useful in evaluating curative effect of MG.3. The expression of Foxp3 in CD4~+CD25~+Treg in peripheral blood is decreased in MG patients. And there are negative correlation between the expression of Foxp3 in CD4~+CD25~+Treg in peripheral blood and the level of AchR-Ab and Titin-Ab , but positive correlation between the level of Titin-Ab and severity of muscle weakness, Therefore it is indicated that Foxp3 test is useful in monitoring immunological function of MG.