Interleukin3

Interleukin‑3 (IL‑3) is a cytokine produced primarily by activated T lymphocytes and mast cells. It belongs to the four‑helix bundle cytokine family and signals through a heterodimeric receptor complex composed of a specific IL‑3 α‑chain and a common β‑chain shared with other cytokines such as IL‑5 and GM‑CSF. IL‑3 promotes the growth, differentiation, and survival of hematopoietic progenitor cells, influencing the development of granulocytes, monocytes, erythrocytes, basophils, and mast cells.

In vitro studies show that IL‑3 enhances proliferation of multipotent hematopoietic progenitors and supports colony formation from both common myeloid and common lymphoid precursors. In vivo, IL‑3 contributes to immune regulation by stimulating the expansion of myeloid cells and modulating the bone marrow microenvironment. The cytokine also has roles in mast cell biology; IL‑3 can augment mast cell proliferation and cytokine release, implicating it in allergic responses.

Genetic analyses have linked variations in the IL‑3 gene with susceptibility to several blood disorders, including thrombocytopenia and certain leukemias. Additionally, IL‑3 has been studied as a potential therapeutic adjuvant in vaccination and cancer immunotherapy due to its ability to recruit and activate antigen‑presenting cells.

Receptor signaling involves activation of the JAK/STAT, MAPK, and PI3K pathways, leading to transcriptional changes that support myeloid lineage commitment and metabolic adjustments. Dysregulation of IL‑3 or its signaling components can contribute to pathological conditions such as myeloproliferative neoplasms and inflammatory disorders. Current research continues to investigate IL‑3’s dual roles in normal hematopoiesis and disease states, aiming to harness its functions for therapeutic benefit.