Peripheral plasmablasts in anti-MuSK myasthenia gravis

For reprints contact: service@oaepublish.com As Hong and Sung previously did, we read with great interest the study published by Guptill et al. They reported that anti-muscle-specific kinase (MuSK) myasthenia gravis patients and healthy controls had similar percentages of peripheral plasmablasts. This result is derived from a comparison between 13 female patients (out of the 18 originally included in the study) and 6 controls. Taking into account the effect of rituximab on peripheral plasmablasts, those patients treated with it (n = 3) were not included in the previous comparison. Excluding these patients, 6 (40%) were on chronic prednisone treatment, whose dose was between 2.5 mg every other day and 20 mg daily. However, it is already known that prednisone therapy effectively decreases peripheral plasmablasts, so this could contribute to the lack of difference between patients and controls. They also reported that immunosuppressed (n = 7) and non-immunosuppressed (n = 6) patients had similar percentages of peripheral plasmablasts. A comparison between non-immunosuppressed patients and controls would have also been quite informative, since it would eliminate the prednisone factor and facilitate the demonstration of a difference between a seemingly normal population of peripheral plasmablasts (controls) and an abnormal one (patients). Finally, vaccination history in controls is also an important point to consider, since it has been documented that peripheral plasmablasts increase after vaccination.