IL-2 augments the therapeutic efficacy of adoptively transferred B cells which directly kill tumor cells via the CXCR4/CXCL12 and perforin pathways.

Yang Xia,Alfred E Chang,Xiubao Ren,Steven K Lundy,Yangyang Hu,Xin Chen,Fu Dai,Qiao Li,Huimin Tao,Yi Wang,Shiang Huang,Quanning Chen,Yangyi Bao,Li Zhou,Leiming Xia

doi:10.18632/oncotarget.11124

Abstract

We previously reported that antitumor B cells directly kill tumor cells via the Fas/FasL pathway and are regulated by IL-10. In this study, we defined additional mechanisms involved in B cell antitumor immunity. Administration of IL-2 significantly augmented the therapeutic efficacy of adoptively transferred tumor-draining lymph node (TDLN) B cells which express IL- 2R. Culture supernatant of purified B splenocytes harvested from the mice that received adoptive transfer of 4T1 TDLN B cells plus IL-2 administration produced larger amounts of IgG which bound to 4T1, resulting in 4T1 lysis. Furthermore, we detected CXCR4 expression on 4T1 TDLN B cells, and 4T1 tumor cells produced its ligand CXCL12. Transwell experiments demonstrated the chemoattraction of CXCR4-expressing 4T1 TDLN B cells towards CXCL12- producing 4T1 cells. Blockade of CXCR4 using a CXCR4-specific inhibitor, AMD3100, significantly reduced the killing of 4T1 tumor cells by 4T1 TDLN B cells. Blockade of FasL and CXCR4 concurrently inhibited B cell-mediated direct killing of tumor cells in an additive manner, indicating that both Fas/FasL and CXCL12/CXCR4 pathways are involved in the direct killing of 4T1 cells by 4T1 TDLN B cells. TDLN B cells produced perforin. Additional transwell experiments showed that effector B cells could directly kill tumor cells in cell-cell contact via the Fas/FasL and CXCR4/CXCL12 pathways as well as perforin, while without cell contact, perforin secreted by B cells led to tumor cell cytotoxicity. These findings underscore the diversity of function by which B cells can play an important role in the host immune response to tumor.

Highlights

We previously reported that simultaneously stimulating CD3 on T cells and CD40 on B cells augments the antitumor reactivity of tumor-draining lymph node (TDLN) cells [1]
In a murine 4T1 model of breast cancer syngeneic to Balb/c mice, we reported that the transfer of LPS/anti-CD40- activated 4T1 tumordraining lymph node (TDLN) B cells significantly reduced the induction of spontaneous 4T1 pulmonary metastases, and these effector B cells could directly kill 4T1 tumor cells [3]
In order to investigate the role of Interleukin 2 (IL-2) in B cell-mediated adoptive immunotherapy, we examined the efficacy of transferred TDLN B cells given in a suboptimal dose (1 x 106 cells/ mouse) in conjunction with or without IL-2 administration

Summary

Introduction

We previously reported that simultaneously stimulating CD3 on T cells and CD40 on B cells augments the antitumor reactivity of tumor-draining lymph node (TDLN) cells [1]. In a murine 4T1 model of breast cancer syngeneic to Balb/c mice, we reported that the transfer of LPS/anti-CD40- activated 4T1 TDLN B cells significantly reduced the induction of spontaneous 4T1 pulmonary metastases , and these effector B cells could directly kill 4T1 tumor cells [3]. Together, these studies demonstrated that transferred effector B cells can act independently in eliciting tumor regression in vivo in several murine tumor models syngeneic to hosts with different genetic backgrounds

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