Assay Development and Measurement of Autoantibody-Mediated Complement Activity in Myasthenia Gravis

Autoantibodies against the acetylcholine receptor (AChR) play a critical role in myasthenia gravis, where autoantibody-mediated complement activation has been implicated in neuromuscular junction damage. However, the exact pathogenic role of the autoantibodies in complement activation remains unclear. We developed a cell-based assay that measures AChR autoantibody–mediated complement membrane attack complex (MAC) formation. A modified HEK293T cell line using CRISPR/Cas9 genome editing to disrupt expression of the complement regulator genes (CD46, CD55, and CD59)—was used to measure AChR autoantibody–mediated membrane attack complex (MAC) formation through flow cytometry. We observed a modest correlation between autoantibody-mediated complement mediated activity and disease burden suggesting heterogeneity in autoantibody-mediated activation of complement system.