Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction of skeletal muscles. Triple-seronegative MG (tSN-MG, without detectable AChR, MuSK and LRP4 antibodies), which accounts for ~ 10% of MG patients, presents a serious gap in MG diagnosis and complicates differential diagnosis of similar disorders. Several AChR antibody positive patients (AChR-MG) also have antibodies against titin, usually detected by ELISA. We have developed a very sensitive radioimmunoprecipitation assay (RIPA) for titin antibodies, by which many previously negative samples were found positive, including several from tSN-MG patients. The validity of the RIPA results was confirmed by western blots. Using this RIPA we screened 667 MG sera from 13 countries; as expected, AChR-MG patients had the highest frequency of titin antibodies (40.9%), while MuSK-MG and LRP4-MG patients were positive in 14.6% and 16.4% respectively. Most importantly, 13.4% (50/372) of the tSN-MG patients were also titin antibody positive. None of the 121 healthy controls or the 90 myopathy patients, and only 3.6% (7/193) of other neurological disease patients were positive. We thus propose that the present titin antibody RIPA is a useful tool for serological MG diagnosis of tSN patients.
Stergiou, C., Lazaridis, K., Zouvelou, V., Tzartos, J., Mantegazza, R., Antozzi, C., Andreetta, F., Evoli Stampanoni-B, A., Deymeer, F., Saruhan Direskeneli, G., Durmus, H., Brenner, T., Vaknin, A., Berrih Aknin, S., Behin, A., Sharshar, T., De Baets, M., Losen, M., Martinez Martinez, P., Kleopa, K. A., Zamba Papanicolaou, E., Kyriakides, T., Kostera Pruszczyk, A., Szczudlik, P., Szyluk, B., Lavrnic, D., Basta, I., Peric, S., Tallaksen, C., Maniaol, A., Gilhus, N. E., Casasnovas Pons, C., Pitha, J., Jakubíkova, M., Hanisch, F., Bogomolovas, J., Labeit, D., Labeit, S., Tzartos, S. J., Titin antibodies in "seronegative" myasthenia gravis - A new role for an old antigen, <<JOURNAL OF NEUROIMMUNOLOGY>>, 2016; 292 (marzo): 108-115. [doi:10.1016/j.jneuroim.2016.01.018] [http://hdl.handle.net/10807/94698]
Titin antibodies in "seronegative" myasthenia gravis - A new role for an old antigen
Evoli Stampanoni-B, Amelia;
2016
Abstract
Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction of skeletal muscles. Triple-seronegative MG (tSN-MG, without detectable AChR, MuSK and LRP4 antibodies), which accounts for ~ 10% of MG patients, presents a serious gap in MG diagnosis and complicates differential diagnosis of similar disorders. Several AChR antibody positive patients (AChR-MG) also have antibodies against titin, usually detected by ELISA. We have developed a very sensitive radioimmunoprecipitation assay (RIPA) for titin antibodies, by which many previously negative samples were found positive, including several from tSN-MG patients. The validity of the RIPA results was confirmed by western blots. Using this RIPA we screened 667 MG sera from 13 countries; as expected, AChR-MG patients had the highest frequency of titin antibodies (40.9%), while MuSK-MG and LRP4-MG patients were positive in 14.6% and 16.4% respectively. Most importantly, 13.4% (50/372) of the tSN-MG patients were also titin antibody positive. None of the 121 healthy controls or the 90 myopathy patients, and only 3.6% (7/193) of other neurological disease patients were positive. We thus propose that the present titin antibody RIPA is a useful tool for serological MG diagnosis of tSN patients.
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