Classical complement pathway factor, C4 is required for experimental autoimmune myasthenia gravis (EAMG) pathogenesis. C4 is also a central component of the mannose binding lectin (MBL) pathway suggesting that this pathway might also be involved in MG pathogenesis. However, MBL gene deficient mice displayed intact anti-acetylcholine receptor (AChR)-immune response and neuromuscular junction (NMJ) IgG and complement accumulation following AChR-immunization. Moreover, no significant difference was observed between the serum MBL levels of 77 anti-AChR antibody positive generalized MG patients and 105 healthy controls. Therefore, MBL pathway does not play a role in EAMG/MG pathogenesis.