Extensive Clinical Flow Cytometric Lymphocyte Phenotyping in Myasthenia Gravis: A Single-Center Study

Myasthenia gravis (MG) is an autoimmune neurological disease characterized by potentially life-threatening muscular fatiguability. Symptoms are directly linked to autoantibodies targeting postsynaptic receptors of the neuromuscular junction. However, the underlying immunopathogenesis remains to be elucidated. This single-center study aimed to characterize peripheral blood lymphocytes in MG patients and to identify prognostic biomarkers. We retrospectively reanalyzed clinical flow cytometric data on blood B and T cells from 76 incident MG cases, comparing them to healthy individuals of relevant age range. Clinical data was collected from the Swedish MG registry and used for outcome analyses. Flow cytometry analyses were based on standardized panels established by the Human Immunology Project Consortium and included a 10-color T cell panel focused on memory, polarization, and activation states and an 8-color B cell panel that includes memory phenotypes, transitional B cells and plasmablasts. Groupwise comparisons, survival curves, and regression models adjusting for potential confounders were used to assess potential predictors of the primary outcome, minimal disease manifestation within one year. Untreated MG patients had higher frequencies of cluster of differentiation 4 (CD4) T cell frequencies compared to healthy individuals of approximately the same age (median 75% vs. 63% in age range 40-59 years and 65% in 60-81 years). High CD4 T cell frequencies (> 75% of total T cells) were associated with lower probability of minimal disease manifestation within one year (35% vs. 67%; log rank p = 0.032). In a multivariable Cox regression model assessing time to minimal disease manifestation, CD4 T cell frequency was an independent risk factor (p = 0.0014). In conclusion, MG patients appear to display an altered CD4 T cell phenotype and frequency of CD4 T cells is a potential prognostic biomarker.