Granulozytopoese

Granulozytopoese, or granulopoiesis, is the process by which granulocytes—neutrophils, eosinophils, and basophils—are formed and mature in the bone marrow as part of myeloid hematopoiesis. It begins with hematopoietic stem cells that commit to the myeloid lineage and progressively restricted progenitors that give rise specifically to granulocyte precursors.

Development proceeds through a defined sequence of precursors: myeloblast, promyelocyte, myelocyte, metamyelocyte, and band cell, culminating in mature granulocytes. Neutrophils are the most abundant circulating granulocytes; eosinophils and basophils arise along parallel sublineages with their own maturation steps. Mature granulocytes are released into the bloodstream and can migrate into tissues as needed; neutrophils have a relatively short circulating lifespan, while eosinophils and basophils can persist longer in inflammatory conditions.

Regulation of granulopoiesis is tightly controlled by cytokines and growth factors. Granulocyte colony-stimulating factor (G-CSF) is the principal driver of neutrophil production, with additional support from GM-CSF and interleukins such as IL-3 and IL-5. Stem cell factor (SCF) and other signaling pathways promote progenitor expansion and survival. Transcription factors including PU.1, C/EBPα, C/EBPε, and GATA-2 coordinate lineage commitment, proliferation, and terminal differentiation.

Clinical relevance of granulopoiesis lies in its disruption or enhancement. Impaired granulopoiesis can cause neutropenia or agranulocytosis, increasing infection risk and often requiring supportive therapies such as granulocyte colony-stimulating factors. Conversely, dysregulated granulopoiesis is observed in certain myeloid disorders and leukemias, influencing diagnosis and treatment strategies.