Folke J, Rydbirk R, Lokkegaard A, et al. - This study was intended to present decreased high-affinity/avidity anti-α-syn naturally occurring autoantibodies (nAbs) in plasma from multiple system atrophy (MSA) and Parkinson disease (PD) patients along with different diverse inter-group immunoglobulin (Ig)G subclass distributions. Researchers evaluated the affinity/avidity of CSF anti-α-syn nAbs and as well as CSF and plasma distribution of IgG and IgM nAbs subclasses using competitive and indirect ELISAs in a cross-sectional cohort of MSA and PD patients. As per the results, variations in the distribution of anti-α-syn nAbs appear to be a common feature in synucleinopathies. The data demonstrate that MSA and PD patients may have a compromised immune reactivity towards α-syn. It has been considered that PD and MSA α-syn-specific systemic immunological responses may reflect their different disease pathophysiology and encourage further investigation of these immunological mechanisms.