IL-21–producing effector Tfh cells promote B cell alloimmunity in lymph nodes and kidney allografts
Hengcheng Zhang, Cecilia B. Cavazzoni, Manuel A. Podestà, Elsa D. Bechu, Garyfallia Ralli, Pragya Chandrakar, Jeong-Mi Lee, Ismail Sayin, Stefan G. Tullius, Reza Abdi, Anita S. Chong, Bruce R. Blazar, Peter T. Sage
Hengcheng Zhang, Cecilia B. Cavazzoni, Manuel A. Podestà, Elsa D. Bechu, Garyfallia Ralli, Pragya Chandrakar, Jeong-Mi Lee, Ismail Sayin, Stefan G. Tullius, Reza Abdi, Anita S. Chong, Bruce R. Blazar, Peter T. Sage
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Research Article Immunology Transplantation

IL-21–producing effector Tfh cells promote B cell alloimmunity in lymph nodes and kidney allografts

Abstract

Follicular helper T (Tfh) cells have been implicated in controlling rejection after allogeneic kidney transplantation, but the precise subsets, origins, and functions of Tfh cells in this process have not been fully characterized. Here we show that a subset of effector Tfh cells marked by previous IL-21 production is potently induced during allogeneic kidney transplantation and is inhibited by immunosuppressive agents. Single-cell RNA-Seq revealed that these lymph node (LN) effector Tfh cells have transcriptional and clonal overlap with IL-21–producing kidney-infiltrating Tfh cells, implicating common origins and developmental trajectories. To investigate the precise functions of IL-21–producing effector Tfh cells in LNs and allografts, we used a mouse model to selectively eliminate these cells and assessed allogeneic B cell clonal dynamics using a single B cell culture system. We found that IL-21–producing effector Tfh cells were essential for transplant rejection by regulating donor-specific germinal center B cell clonal dynamics both systemically in the draining LN and locally within kidney grafts. Thus, IL-21–producing effector Tfh cells have multifaceted roles in Ab-mediated rejection after kidney transplantation by promoting B cell alloimmunity.

Authors

Hengcheng Zhang, Cecilia B. Cavazzoni, Manuel A. Podestà, Elsa D. Bechu, Garyfallia Ralli, Pragya Chandrakar, Jeong-Mi Lee, Ismail Sayin, Stefan G. Tullius, Reza Abdi, Anita S. Chong, Bruce R. Blazar, Peter T. Sage

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Figure 1

IL-21–producing Tfh cells are generated in LNs and grafts after allogeneic kidney transplantation.

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IL-21–producing Tfh cells are generated in LNs and grafts after allogene...
(A) Schematic of kidney transplantation. (B) Gating strategy (left) and quantification of FAS+CD38– GC B cells (right) in the spleen and dLN. (C) DSA IgG measurements from serum. (D) Histology and C4d IF in grafts. Scale bars: 100 μm; original magnification: ×100. (E) Quantification of Tfh (CD4+CD19–CXCR5+ICOS+GITR–) cells in the spleen and dLN. Representative gating (left) and quantification (right) are shown. (F) Gating strategy (left) and quantification (right) of IL-21 fate mapped (YFP+) Tcon and Tfh cells. Gated on CD4+CD19–CXCR5+ICOS+ cells. (G) Expression of ICOS in IL-21 fate-mapped (IL-21+) or nonfate-mapped (IL-21–) Tfh cells. (H) Schematic of kidney transplantation of Balb/c kidneys into IL-21 direct reporter mice. (I) Gating strategy (left) and quantification (right) of total Tfh cells. (J) Gating strategy (left) and quantification (right) of IL-21–expressing (VFP+) Tfh cells. (K) Frequency (left) and MFI (right) of VFP+ cells in ICOS low and high Tfh cells. gMFI, geometric MFI. (L and M) Quantification of IL-21–producing (YFP+, and VFP+) graft-infiltrating CD4+ T cells. In A–M, data are combined from 2 independent experiments, n = 2–5 mice replicates per group. (N) Schematic of in vitro Tfh-mediated B cell stimulation assay. IL-21 fate-mapped (IL-21+), nonfate-mapped (IL-21–) Tfh, and B cells from recipients were cocultured for 4 days with anti-CD3/IgM. (O) Gating strategy (left) and quantification (right) of activated (GL7+) B cells. (P) IgG concentration in culture supernatants of the in vitro assays. In O and P, data are from 1 experiment and are representative of 2 independent experiments, n = 5–6 wells per group. Student’s 2-tailed unpaired t test for G, 1-way ANOVA with Tukey’s multiple comparison test for O and P. *P < 0.05; **P < 0.01; ***P < 0.001.