Introduction: CD4+CD25+ regulatory T-lymphocytes (T-regs) and regulators of complement activity (RCA) involving CD55 and CD59 play an important role in the prevention of autoimmune diseases. However their role in the pathogenesis of human autoimmune myasthenia gravis (MG) remains unclear. This study aimed to determine the frequency of peripheral blood T-regs and CD4+ T-helper (T-helper) cells and the RBCs level of expression of CD55 and CD59 in MG patients.

Methods: Fourteen patients with MG in neurology outpatient clinics of Sohag University Hospital, and Sohag General Hospital from March 2014 to December 2014, and ten age matched healthy controls participated in this case-control study. We did flowcytometric assessments of the percentage of peripheral T-regs and T-helper cells and the level of expression of CD55 and CD59 on RBCs in the peripheral blood of patients and controls.

Results: There was a statistically significant decrease in the percentage of peripheral blood T-regs and T-regs/T-helper cell ratio in the MG patients group. Moreover, the level of expression of CD55, CD59 and dual expression of CD55/CD59 on RBCs were statistically significantly lower in MG patients than those of healthy controls. However; regression analysis revealed that there was no significant correlation between all the measured parameters and disease duration or staging.

Conclusion: Functional defects in the T-regs and RCA may play a role in the pathogenesis of autoimmune MG and their functional modulation may represent an alternative therapeutic strategy for MG treatment.