Utility of Live Cell-Based Assays for Autoimmune Neurology Diagnostics

Antibodies that recognize epitopes on the extracellular surface of integral membrane or membrane-associated proteins in the CNS (central nervous system) are associated with severe, treatable, autoantibody-mediated neurologic diseases. Twenty such antibodies have been discovered since 2004 (1). These human antibodies recognize conformationally native epitopes which has promoted the development of cell-based assays (CBAs) where mammalian cells are induced to express the native protein target on their cell surface. Patient serum, plasma, or CSF (cerebrospinal fluid) are then incubated with these cells and target-specific antibodies are identified by fluorescent secondary antibodies. Antibody levels are determined by end point titer microscopically or quantitatively by flow cytometry. A control antigen tested in parallel helps demonstrate antibody specificity (Fig. 1, A) Before making contact with a patient sample, cells are either living or chemically modified. Live cells present the conformationally native antigen. However, maintenance of living cells requires a specialized...