Increased PD-1+CD154+ Tfh cells are possibly the most important functional subset of PD-1+ T follicular helper cells in adult patients with minimal change disease

T follicular helper (Tfh) cells, especially programmed cell death protein 1 (PD-1)+ Tfh cells, exert important functions in the normal immune response. The purpose of this study was to determine the frequency of different subsets of PD-1+ Tfh cells and their functional effects in adult patients with minimal change disease (MCD). The frequencies of circulating PD-1+, PD-1+CD154+, and PD-1+interleukin (IL)-21+ Tfh cells, and CD38+CD19+ and CD38+CD19+CD40+ B cells, as well as serum IL-2, IL-4, IL-17A, IL-6, IL-21, and interferon (IFN)-γ were significantly increased in the MCD patients compared with the healthy controls (HCs) (P < 0.05). However, no significant difference was found in PD-1+BCL-6+ or PD-1+ICOS+ Tfh cells. Furthermore, the percentages of PD-1+ Tfh and PD-1+CD154+ Tfh cells were negatively correlated with the estimated glomerular filtration rate (eGFR), but positively correlated with the 24-h urinary protein concentration and serum IL-21 level. The percentages of PD-1+ Tfh and PD-1+CD154+ Tfh cells were positively correlated with the percentages of CD38+ plasma cells and active CD38+CD40+ plasma cells, respectively. After an 8-12-week treatment with prednisolone, the percentages of PD-1+, PD-1+CD154+, and PD-1+IL-21+ Tfh cells as well as the serum level of IL-21 were significantly reduced; in contrast, the serum levels of IL-4 and IL-10 were increased (P < 0.05). We conclude that increased PD-1+CD154+ Tfh cells are possibly the most important functional subset of PD-1+ Tfh cells and may contribute towards the pathogenesis of MCD.