[The role of CD4+ CD25+ T cells in the mechanism of myasthenia gravis in children and adults].

OBJECTIVE: To investigate the role of CD4+CD25+ regulatory T cells in the mechanism of myasthenia gravis (MG) in children and adults.

METHODS: Peripheral blood samples were collected from 13 MG patients, 5 being aged > 14 and 8 being aged <or= 14, and 10 age-matched healthy persons. Peripheral blood mononuclear cells were isolated. Flow cytometry was used to examine the rate of CD4+CD25+ regulatory T cells (Tregs). Fluorescence-activated cell sorter was used to detect the expression of Foxp3 and CTLA-4, 2 important functional markers of CD4+CD25+ Tregs.

RESULTS: The percentage of CD4+CD25+ Tregs of the MG children was significantly higher than that of the healthy children (P < 0.05), and the percentage of CD4+CD25+ Tregs of the MG adults was higher then that of the healthy adults, but not significantly (P = 0.795). The expression level of Foxp3 of the MG children was significantly lower than that of the healthy children (P = 0.011), and the expression level of Foxp3 of the MG adults was not significantly different from that of the healthy adult controls (P = 0.084). The expression levels of CTLA-4 of both the MG children and adults were lower than those of the healthy children and adults, but not significantly (P = 0.556, P = 0.767).

CONCLUSION: The CD4+CD25+ Tregs in peripheral blood from MG pediatric patients are increased in number but unable functionally. The pathogenesis of MG in children may be correlated with the impairment of immunotolerance of the peripheral blood Tregs.