| Background:Myasthenia Gravis is an autoimmune neuromuscular disease caused by a defect in the transmission of nerve impulses to muscles which mediated by antibodies to nicotinic acetylcholine receptors (AChR) in T cell dependent immune responses. The body immune system plays an important role in the balance of immunity and self tolerance. The infectious antigen tolerance is the key point to prevent autoimmune diseases. Regulatory T cells (Treg) are involved in the establishment of peripheral tolerance mechanisms which inhibit autoreactive T cells activation and proliferation. In addition, Regulatory T cells have a crucial role in controlling tolerance to self antigens and alloantigens in clinical course of Myasthenia Gravis .Related research found that Treg cells can express many types of surface molecules, such as CD25, CD28/CTLA-4, GITR, Nrp-1 uropilin-1), CD27, CD62L and CD127, etc., but highly specific markers have not been found yet. CD25 is the alpha chain of the IL-2 receptor. High expression of CD25 surface markers is used to identify activated Treg cells. At present, researches for Treg cells have become a topic of general interest. Present studies have confirmed that there are abnormalities with regulatory T cells in MG patients, and they play an important role in the occurrence and development of MG. But there are still many issues unclear. for example the reason which cause the quantity changes and functional defects of Treg cells haven't been figured out, in particular, the means by which Tregs cells inside the body cause the issue of MG, and the correlation between Treg cells and the clinical features etc .Meanwhile there are not many researches on the relations between quantity abnormality or dysfunction of Tregs and MG treatment and prognosis. If we can make clear the mechanism of Treg cells and by some means or method regulate the quantity and function effectivly in self-antigen and alloantigen, we'll achieve more in the mechanism and the therapy in MG.Objective:This research illustrates the changes in the number of regulatory T (Treg) cells contributes to the onset of MG, analyses the relation between the clinical classification of regulatory T cells and the prognosis.Method:1.Immunohistochemistry detection (S-P method) was carried out to detect the expression of CD25 in thymus sections of 37 cases diagnosed with MG's and treated by thymusectomy. 2.Aim to study the relationship between the expression of CD25 + Treg cells and the clinical features of MG patients, including age and gender.3.To investigate the relationship between expression of CD25 + Treg cells and MGFA types.4.All patients after operation were followed up to study the expression of CD25 in thymus sections and its correlation with prognosis.Results:1. CD25 + Treg cells in MG group compared with normal control group:CD25 + Treg cells in MG group and normal control group showed similar distribution, mainly in the trabecular spacing and thymic medulla region. In addition, they also thinly distribute in thymus cortex. There were CD25+ Treg cells around the germinal center, thymic corpuscles (Hassall's Body) and the lymphoid follicles in MG thymus hyperplasia group. Compared with the normal controls, the expression of CD25 positive in MG thymus hyperplasia group was significantly higher, while the MG thymoma group was rather low with only a few cells expressed CD25.In the MG thymic cyst group the expression was similar to normal controls.The Intergrated optical density(IOD) value of immunohistochemical staining showed that Compared with the normal controls, the expression of CD25 positive in MG thymus hyperplasia group increased significantly(P<0.05). The MG thymoma group decreased significantly (P<0.05). .In the MG thymic cyst group the expression was similar to normal controls,.There was no significant difference between the two groups(P <0.05).2. The relationship between the expression of CD25+ Treg cells and the clinical features of MG patients, including age and gender.In MG patients, 24 cases with an age at onset of myasthenia gravis <50 years formed the early onset myasthenia gravis group (EOMG), and patients with an age at onset > 50 years formed the late onset myasthenia gravis group (LOMG). It is less frequent that EOMGassociated with thymoma than the LOMG. The ratio of EOMG associated with thymoma was 20.8% (5//24), while LOMG was 38.5% (5/13). The IOD value of immunohistochemical staining showed that the expression of CD25 positive in EOMG has no significant changes compared with LOMG in all three group (P<0.05). The expression of CD25 has no relation to the gender of MG patients in all three group. There was no significant difference (P <0.05).3. The relationship between expression of CD25 + Treg cells and MGFA types.The expression of CD25 is related with the MGFA type of MG Patients. In the MG thymus hyperplasia group, the expression of CD25 were significantly different between MGFA I type and MGFA IIa type (P <0.01). With the classification of MGFA elevating, the expression of CD25 increased.4. The relationship between the expression of CD25 in thymus sections and its correlation with thymectomy effect and prognosis.By analyzing the recovered group, partial remission group and invalid group, the expression of CD25 in the MG thymus hyperplasia group were different (P <0.01). In the MG thymus hyperplasia group, the recovered group expresses more CD25 than the partial remission group, while the partial remission group expresses more CD25 than the invalid group.Conclusion:1. CD25 + Treg cells in MG group and normal control group showed similar distribution.The Intergrated optical density(IOD) value of immunohistochemical staining showed that :Compared with the normal controls, the expression of CD25 positive in MG thymus hyperplasia group increased significantly. The MG thymoma group decreased significantly. .In the MG thymic cyst group the expression was similar to normal control.Dysimmunity in thymus is the reason.2. It is less frequent that EOMG associated with thymoma than the LOMG. The expression of CD25 in EOMG increases more significantly than LOMG.3. The expression of CD25 + Treg cells has relation to the MGFA classification. The expressions of CD25 in all MGFA types were significantly different. With the classification of MGFA elevating, the expression of CD25 increased.4. The expression of CD25 in thymus section has relation to the prognosis of MG patients after thymectomy. The recovered group expresses more CD25 than the partial remission group, while the partial remission group expresses more CD25 than the invalid group. |
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