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 6

IL-21–producing Tfh cells mediate GC B cell dynamics in LNs and kidney grafts.

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IL-21–producing Tfh cells mediate GC B cell dynamics in LNs and kidney g...
(A) Schematic of IL-21–producing Tfh cell deletion using F/Ex-DTR mice. Control (Il21CreRosa26Lox-STOP-Lox-YFPCxcr5WT) or F/Ex-DTR (Il21CreRosa26Lox-STOP-Lox-YFPCxcr5Lox-STOP-Lox-DTR) mice were transplanted with a Balb/c kidney and cells deleted with administration of DT. (B) Quantification of total B cells (gated as CD45+CD19+CD4–) in dLNs. (C) Gating strategy (left) and quantification (right) of GC B cells, IgG1+ GC B cells, and CD138+ plasmablast/plasma cells in the dLN. (D) Quantification of naive B, GC-like B cells (CD45+CD19+CD4–GL7+FAS+), and CD138+ cells in kidney grafts. (E) Assessment of VH segment somatic hypermutation in LN GC B (CD19+GL7+FAS+) and Graft B (CD45+CD19+) cells. (F) Frequency of IgG+ cells from BCR sequencing in (E). (G) Clonal expansion of B cells in dLN. Same clone was defined as greater than 80% CDRH-3 aa sequence identity, same V-J segments, and CDRH-3 length. Numbers indicate total unique clones/total sequences. (H) Schematic of single B cell clonal assays. Single GC B cells from dLN or B cells from grafts were sorted and cultured with NB21 feeder cells for 6 days. Culture supernatants were prescreened for IgG positivity and further assessed for DSA reactivity. (I) DSA reactivity of individual IgG+ clones from LN GC B and graft B cells from either control or F/Ex-DTR mice 40 days after transplantation. Dotted line indicates level of detection threshold. (J) Frequency of DSA reactive clones (out of IgG+ clones). Numbers indicate the total number of IgG clones analyzed. (K) IF staining of allokidneys using top 5 alloreactive dLN clones from J. Positive signal: red; DAPI: blue. Scale bars: 100 μm; original magnification: ×100. Data are combined from 2 independent experiments with n = 4–5 mice per group. Student’s 2-tailed unpaired t test for B–D and Mann-Whitney test for E for 2-group comparisons. *P < 0.05; **P < 0.01; ***P < 0.001.