Interleukin-7 Biology and Its Effects on Immune Cells: Mediator of Generation, Differentiation, Survival, and Homeostasis.

Deng Chen,Xiang-Ping Yang,Ting-Xuan Tang,Hai Deng,Zhao-Hui Tang

doi:10.3389/fimmu.2021.747324

Abstract

Interleukin-7 (IL-7), a molecule known for its growth-promoting effects on progenitors of B cells, remains one of the most extensively studied cytokines. It plays a vital role in health maintenance and disease prevention, and the congenital deficiency of IL-7 signaling leads to profound immunodeficiency. IL-7 contributes to host defense by regulating the development and homeostasis of immune cells, including T lymphocytes, B lymphocytes, and natural killer (NK) cells. Clinical trials of recombinant IL-7 have demonstrated safety and potent immune reconstitution effects. In this article, we discuss IL-7 and its functions in immune cell development, drawing on a substantial body of knowledge regarding the biology of IL-7. We aim to answer some remaining questions about IL-7, providing insights essential for designing new strategies of immune intervention.

Highlights

Interleukin-7 (IL-7) was discovered in the last century and noted for its growth-promoting effects on progenitors of B cells in vivo [1]
IL-7Ra is expressed in early thymocytes, T cells, pre-B cells, bone marrow (BM) macrophages, and other immune cells
The findings indicate that IL-7 can promote the development of early thymic progenitors (ETPs)

Summary

INTRODUCTION

Interleukin-7 (IL-7) was discovered in the last century and noted for its growth-promoting effects on progenitors of B cells in vivo [1]. IL-7R is a heterodimeric complex consisting of the a-chain (CD127) and the common cytokine receptor gchain, shared with the receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, and expressed in a variety of cells [3]. IL-7 has multiple biological activities and influences various cell types through binding to its receptor. Deficiencies in IL-7 or IL-7R can lead to severely impaired immune cell development (Table 1). The discovery of relevant signaling pathways was accompanied by recognition that IL-7 plays an indispensable role in the development and maintenance of many other immune cells. The vital regulatory functions of IL-7 throughout the entire immune system have become increasingly evident

Decrease in DC count

Findings

CONCLUSION AND UNANSWERED QUESTIONS