The primary objective of the study is to longitudinally profile immunoglobulin levels and autoantibody levels in subjects with myasthenia gravis (MG) who receive therapeutic plasma exchange (TPE).
This is a prospective, multi-center, pilot biomarker study in subjects receiving TPE for the treatment of MG. No study medications will be given. Ten (10) AChR antibody positive MG subjects will be enrolled in the study at 2 sites. Of these 10 MG subjects, up to 5 may be receiving chronic TPE. The study period will be approximately 3 months and will consist of: * Screening/baseline visit, * TPE visit where subjects will undergo clinical evaluations and blood draws for immunological assays, * End of TPE visit where information on the TPE procedure will be recorded, clinical measurements will be performed, and a blood sample will be drawn. * Post-TPE period where subjects will undergo clinical evaluations and blood draws for immunological assays at week 1, week 2, week 3, week 6, and week 12 after TPE. Study procedures performed outside of usual care will include optional single-fiber electromyography (SFEMG) studies, blood draws and optional skin biopsies.
Study Type
OBSERVATIONAL
Enrollment
11
An optional skin biopsy will be performed in up to 5 subjects at baseline and 2 weeks after therapeutic plasma exchange is completed.
An optional SFEMG study will be performed at baseline and 2 weeks after therapeutic plasma exchange is completed.
UNC Chapel Hill
Chapel Hill, North Carolina, United States
Duke University Hospital
Durham, North Carolina, United States
Immunoglobulin levels
Immunoglobulin and IgG subtype levels, AChR autoantibody levels, IgG/autoantibody ratio will be listed, summarized and plotted graphically by visit.
Time frame: 14 weeks
Lymphocyte subpopulations
Peripheral blood mononuclear cells (PBMC) will be analyzed using highly standardized polychromatic flow cytometric techniques for the expression of a broad array of phenotypic markers. A B-cell and T-cell panel will be used to profile specific marker expression among PBMCs and define lymphocyte subpopulations.
Time frame: 14 weeks
SFEMG
The extensor digitorum communis muscle will be studied in every subject and the muscle tested must have increased jitter at the initial study. If examination of the extensor digitorum communis is not feasible or the jitter is normal at the initial study, the muscle to study will be at the discretion of the investigator performing the SFEMG test, preferably frontalis. In each SFEMG study, jitter from 20 paired muscle fiber potentials will be recorded whenever feasible. Recorded variables will include total number of muscle fiber pairs studied, abnormal muscle fiber pairs, blocking pairs, and mean consecutive difference (MCD).
Time frame: 14 weeks
Vaccination/protective antibodies
The time course for recovery of selected protective antibody levels removed during TPE will be summarized.
Time frame: 14 weeks
Clinical Outcomes Assessments
All clinical outcomes assessments data (MG-Composite, MG-ADL, MG-QOL-15, MG-MMT) will be listed and summarized by visit. Scores may be presented graphically. Immunological measurements will be correlated with clinical scores, if appropriate.
Time frame: 14 weeks
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