TCR Repertoire Analysis Reveals Mobilization of Novel CD8+ T Cell Clones Into the Cancer-Immunity Cycle Following Anti-CD4 Antibody Administration.

Hiroyasu Aoki,Haru Ogiwara,Satoshi Ueha,Shin-Ichi Hashimoto,Satoru Ito,Shigeyuki Shichino,Kouji Matsushima,Kazuhiro Kakimi

doi:10.3389/fimmu.2018.03185

Abstract

Depletion of CD4+ cells using an anti-CD4 monoclonal antibody (anti-CD4 mAb) induces the expansion of tumor-reactive CD8+ T cells and strong antitumor effects in several murine tumor models. However, it is not known whether the anti-CD4 mAb treatment activates a particular or a broad spectrum of tumor-reactive CD8+ T cell clones. To investigate the changes in the TCR repertoire induced by the anti-CD4 mAb treatment, we performed unbiased high-throughput TCR sequencing in a B16F10 mouse subcutaneous melanoma model. By Inter-Organ Clone Tracking analysis, we demonstrated that anti-CD4 mAb treatment increased the diversity and combined frequency of CD8+ T cell clones that overlapped among the tumor, draining lymph node (dLN), and peripheral blood repertoires. Interestingly, the anti-CD4 mAb treatment-induced expansion of overlapping clones occurred mainly in the dLN rather than in the tumor. Overall, the Inter-Organ Clone Tracking analysis revealed that anti-CD4 mAb treatment enhances the mobilization of a wide variety of tumor-reactive CD8+ T cell clones into the Cancer-Immunity Cycle and thus induces a robust antitumor immune response in mice.

Highlights

Immune checkpoint inhibitor treatments such as blocking antibodies against cytotoxic T-lymphocyte associated protein 4 (CTLA-4) and programmed death receptor 1 (PD-1) have produced remarkable clinical effects in several kinds of malignancies [1,2,3]
Flow cytometry analyses revealed the successful induction of B16 reactive Pmel-1 CD8+ T cells following aCD4 mAb treatment in the draining lymph node (dLN) CD44hi; in the aCD4 group, the frequency of Pmel-1 T cells tended to increase in dLN CD44hi
We focused on two tumor-reactive CD8+ T cell clones; gp100 melanoma antigen-specific Pmel-1 [22] and B16F10 Reactive Clone 1 (B16RC1), which was originally cloned from CD137high CD8+ tumor infiltrating leukocytes (TILs) in B16F10 tumor model [23]

Summary

Introduction

Immune checkpoint inhibitor treatments such as blocking antibodies against cytotoxic T-lymphocyte associated protein 4 (CTLA-4) and programmed death receptor 1 (PD-1) have produced remarkable clinical effects in several kinds of malignancies [1,2,3]. The antitumor effects induced by anti-CD4 depleting monoclonal antibodies (antiCD4 mAb) were found to be mediated by CD8+ cytotoxic T lymphocytes (CTLs), which increased in the draining lymph node (dLN) and tumor after anti-CD4 mAb treatment [7]. The enhancement of CD8+ T cell responses can be explained by the depletion of several immunosuppressive CD4+ cells including forkhead box P3 (Foxp3)+ CD4+ regulatory T cells (Tregs). It is not known whether the anti-CD4 mAb treatment expands a part of the highly activated tumor-specific CTL clones or mobilizes a wide variety of tumor-reactive CD8+ T cell clones into the antitumor CTL response

Methods

Results

Conclusion