Interleukin7

Interleukin-7 (IL-7) is a cytokine that plays a central role in T cell development and homeostasis. It is produced mainly by non-hematopoietic stromal cells in the bone marrow and thymus, as well as by other tissues, and acts on cells expressing the IL-7 receptor.

IL-7 signals through a receptor composed of the IL-7 receptor alpha chain (CD127) and the common gamma chain (CD132). Binding activates JAK1 and JAK3, leading to downstream signaling via STAT5 and often involving PI3K-AKT and MAPK pathways. This signaling supports T cell survival and homeostatic proliferation, in part by upregulating anti-apoptotic proteins such as Bcl-2. IL-7 receptor alpha is typically high on naive and memory T cells and is downregulated upon activation.

Physiological role includes essential participation in thymic T cell development (thymopoiesis) and, in the periphery, maintenance of the naive and memory T cell pool. IL-7 helps preserve T cell receptor repertoire diversity, particularly during lymphopenia when IL-7 levels increase and promote homeostatic T cell expansion.

Clinical and research aspects involve the use of recombinant human IL-7 (rhIL-7) in trials to accelerate T cell reconstitution after chemotherapy or hematopoietic stem cell transplantation and to enhance immune recovery in HIV infection or certain cancers. It can increase CD4+ and CD8+ T cell counts and is generally well tolerated, though concerns include potential lymphoproliferation or expansion of autoreactive T cells. As a result, IL-7 signaling pathways are also explored as therapeutic targets in autoimmune diseases and graft-versus-host disease.