The disturbance and clinical significance of B cell and circulating follicular helper T cell subsets in children with primary nephrotic syndrome.

The immunopathogenesis of primary nephrotic syndrome is unclear. Here, we examined the frequency, subsets and molecular function of circulating B cells and follicular helper T cells by flow cytometry and explored the correlation between certain subsets and clinical disease indices in new-onset patients, relapsing patients and healthy controls. We found an increase in the proportions of CD86+ activated cells and CD19+CD138+ plasma cells in the patients at onset and patients in relapse. However, the increased percentage of CD27+ memory cells was observed in only the relapse group. Furthermore, the ICOS MFI was elevated in TFH cells and their three subsets in new-onset patients, whereas the expression of OX40 was increased in TFH cells, TFH17 cells and TFH2 cells in the relapse group. Additionally, the increased frequency of CD19+CD138+ plasma cells was positively associated with urea nitrogen in the new-onset groups. Notably, the positive correlation between CD86+ activated B cells and CD19+CD138+ plasma cells was obtained in only the new-onset group and HC group; however, the increased CD27+ memory cell percentage was positively correlated with 24-h urinary protein in only the relapse group. Our results indicate that CD19+CD138+ plasma cells may be a key factor for the onset of PNS, whereas CD27+ memory cells may play a more important role in the relapse of this disease. Furthermore, the functions of TFH cells are also diverse because the expression of vital molecules changes during the different disease phases.