A prospective, placebo controlled study on the humoral immune response to and safety of tetanus revaccination in myasthenia gravis

To investigate the humoral immune response to and safety of a tetanus revaccination in patients with myasthenia gravis or Lambert-Eaton myasthenic syndrome. A tetanus revaccination was administered to 66 patients. Before and 4weeks after revaccination a blood sample and clinical outcome scores were obtained. Anti-tetanus IgG total, IgG1 and IgG4 titres were measured with an ELISA and disease-specific antibody titres (AChR, MuSK or VGCC) with a radio-immunoprecipitation assay. A historic healthy control group was used for comparing tetanus antibody titres with that of our patients. A placebo (saline) vaccination group was used to investigate the variability of clinical outcome scores with a 4weeks interval. In 60 of 65 patients, a significant increase of the anti-tetanus antibody response was measured. Thymectomy did not have an impact on this responsiveness. Patients with immunosuppressive medication had a significantly lower pre and post titre compared to healthy controls, but their response was still significant. The titres of disease-specific antibodies were unchanged 4weeks after revaccination. The clinical outcome scores showed no exacerbation of symptoms of the disease. A tetanus revaccination in patients with myasthenia gravis or Lambert-Eaton myasthenic syndrome is safe and induces a significant immune response, irrespectively of their immunosuppressive medication. We observed neither immunological nor clinical relevant exacerbations associated with the tetanus revaccination. The tetanus trial is listed on clinicaltrialsregister.eu under 2014-004344-35. The placebo AChR MG group was part of another clinical trial, investigating influenza vaccination in myasthenic patients. This trial is listed on clinicaltrialsregister.eu under 2016-003138-26.