Modified radioimmunoassay versus ELISA to quantify anti-acetylcholine receptor antibodies in a mouse model of myasthenia gravis.

In mouse models of myasthenia gravis (MG), anti-acetylcholine receptor (AChR) antibodies can be quantified to monitor disease progression and treatment response. In mice, enzyme-linked immunosorbent assay (ELISA) is the gold standard to quantify these antibodies. However, this method requires antigen purification, which is both time-consuming and expensive. In humans, radioimmunoassay (RIA)-which is more sensitive than ELISA-is commonly used to quantify AChR antibodies. At present, however, no commercial RIA kits are available to quantify these antibodies in mice. The aim of this study was to compare a modified commercial human RIA kit to two ELISA methods to detect AChR antibodies in an experimental autoimmune mouse model of MG (EAMG). C57BL/6 J mice were immunized with purified AChR from Tetronarce californica (T-AChR). Serum samples were analyzed by RIA and two ELISAs (T-AChR and purified mouse AChR peptide [m-AChR]). The modified RIA showed excellent sensitivity (84.1 %) and specificity (100 %) for the detection of AChR antibodies. RIA showed a good agreement with T-AChR ELISA (κ = 0.69) but only moderate agreement with m-AChR ELISA (κ = 0.49). These results demonstrate the feasibility of modifying a commercially-available RIA kit to quantify AChR antibodies in EAMG. The advantage of this technique is that it eliminates the need to develop the entire methodology in-house and reduces inter and intra-laboratory variability.

Inter-laboratory comparison of routine autoantibody detection methods for autoimmune neuropathies and myasthenia gravis.

Serological tests are important to detect autoantibodies (autoAbs) in patients with autoimmune neuropathies (AN) and myasthenia gravis (MG) as they are biomarkers for diagnosis, stratification, treatment selection, and monitoring. However, tests to detect autoAbs frequently lack proper standardization and results differ across diagnostic laboratories. We compared results for tests routinely performed in Spanish diagnostic laboratories to detect AN and MG autoAbs. In the Spanish Society of Immunology Autoimmunity Group national workshop, serum samples from 13 patients with AN or MG were tested for anti-ganglioside, anti-myelin-associated glycoprotein (MAG), anti-nicotinic acetylcholine receptor (AChR), and anti-muscle-specific kinase (MuSK) autoAbs using reference methods and were distributed for analysis to 27 participating laboratories using their routine methods. Overserved were inter-laboratory variability and worryingly low sensitivity, especially for anti-ganglioside immunoglobulin G and anti-MAG autoAb detection. This pilot study reflects autoAbs detection state of the art in AN and MG testing in leading diagnostic laboratories in Spain, highlighting the need for standardization prior to clinical use.