Differential Scanning Calorimetry as a Monitoring Tool for the Effectiveness of Therapeutic Plasma Exchange in Anti-AChR Myasthenia Gravis, Anti-MuSK Myasthenia Gravis, and Myasthenic Syndrome: A Case Series

<b>Background/Objectives:</b> Myasthenia Gravis (MG) and myasthenic syndrome (MSyn) are neurological disorders induced by different types of autoantibodies, characterized by generalized muscle weakness, sometimes involving the respiratory muscles and necessitating ventilatory support. One therapeutic option for severe Myasthenia Gravis (MG) is total plasma exchange (TPE). This procedure reduces the concentration of autoantibodies by extracting the patient's plasma and replacing it with donor plasma. The TPE efficacy varies among different types of MG, and patient response to TPE is evaluated solely through clinical markers, such as muscle strength. So far, no laboratory method is available for monitoring TPE treatment progress. <b>Objective:</b> In this study, we aimed to determine whether differential scanning calorimetry (DSC) of blood plasma from myasthenic patients is an appropriate tool to monitor and evaluate their condition and the TPE effect. <b>Methods:</b> We performed DSC prior to and after TPE course on blood plasma from three patients with different types of MG: Case 1. Patient with Acetylcholine Receptor Myasthenia Gravis (AChR MG); Case 2. Patient with Muscle-specific tyrosine kinase Myasthenia Gravis (MuSK MG); Case 3. Patient with Myasthenic syndrome (MSyn). <b>Results:</b> DSC thermogram examination revealed increased plasma protein fractions, primarily immunoglobulins (IG), as well as to some extent fibrinogen, relative to a suppressed serum albumin fraction. Successive TPE procedures resulted in IG fraction decline in AChR MG (Case 1) and MSyn (Case 3), and upsurge of the IG fraction in MuSK MG (Case 2). These findings aligned with the clinical presentation of all three cases. <b>Conclusions:</b> DSC revealed distinct, very significant differences in the heat capacity profiles of blood plasma from MG patients relative to healthy controls, as well as strong TPE influence on the plasma thermal behavior. DSC showed promise as a reliable and informative technique for the monitoring of myasthenia and TPE effects across diverse myasthenic patient populations. Further research is needed to confirm and expand on these findings.