High frequencies of circulating Tfh-Th17 cells in myasthenia gravis patients

Recent studies show that the frequencies of circulating follicullar helper T (cTfh) cells are significantly higher in myasthenia gravis (MG) patients compared with healthy controls (HC). And, they are positively correlated with levels of serum anti-acetylcholine receptor antibody (anti-AchR Ab). It is unclear whether cTfh cell subset frequencies are altered and what role they play in MG patients. In order to clarify this, we examined the frequencies of cTfh cell counterparts, their subsets, and circulating plasmablasts in MG patients by flow cytometry. We determined the concentrations of serum anti-AChR Ab by enzyme-linked immunosorbent assay (ELISA). We assayed the function of cTfh cell subsets by flow cytometry and real-time polymerase chain reaction (RT-PCR). We found higher frequencies of cTfh cell counterparts, cTfh-Th17 cells, and plasmablasts in MG patients compared with HC. The frequencies of cTfh cell counterparts and cTfh-Th17 cells were positively correlated with the frequencies of plasmablasts and the concentrations of anti-AChR Ab in MG patients. Functional assays showed that activated cTfh-Th17 cells highly expressed key molecular features of Tfh cells including ICOS, PD-1, and IL-21. Results indicate that, just like cTfh cell counterparts, cTfh-Th17 cells may play a role in the immunopathogenesis and the production of anti-AChR Ab of MG.