myeloid progenitor
Summary
A myeloid progenitor (common myeloid progenitor, CMP) is a hematopoietic stem cell-derived precursor that gives rise to erythrocytes, platelets (via megakaryocytes), granulocytes (neutrophils, eosinophils, basophils), monocytes, and mast cells. It arises from the pluripotent hematopoietic stem cell and diverges from the common lymphoid progenitor lineage. Understanding this lineage is key to interpreting hematologic malignancies (e.g., AML) and cytopenias.
Detail
Myeloid progenitors originate from multipotent hematopoietic stem cells (HSCs) in the bone marrow. The HSC first differentiates into either a common myeloid progenitor (CMP) or a common lymphoid progenitor (CLP). The CMP further differentiates into two main branches: (1) the megakaryocyte-erythroid progenitor (MEP), which produces erythrocytes and platelets, and (2) the granulocyte-monocyte progenitor (GMP), which produces neutrophils, eosinophils, basophils, and monocytes/macrophages. Mast cells and dendritic cells can also arise from myeloid progenitors.
Key transcription factors regulate this differentiation: GATA-1 drives erythroid/megakaryocytic lineage commitment, while PU.1 and C/EBPα drive granulocyte/monocyte differentiation. Cytokines such as erythropoietin (EPO), thrombopoietin (TPO), granulocyte colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) act on specific progenitor stages to promote lineage-specific proliferation and maturation.
Clinical relevance: Myeloid progenitors are the cell of origin for myeloproliferative neoplasms (e.g., polycythemia vera, essential thrombocythemia, chronic myeloid leukemia) and acute myeloid leukemia (AML), where genetic mutations (e.g., JAK2, BCR-ABL, FLT3, NPM1) cause uncontrolled proliferation or blocked differentiation at the progenitor stage. Bone marrow failure syndromes (aplastic anemia, myelodysplastic syndromes) also affect myeloid progenitor pools, leading to cytopenias. Flow cytometry markers such as CD34 (stem/progenitor marker), CD13, CD33 (myeloid markers) help identify these cells in diagnostic workups.
Sources
- First Aid for the USMLE Step 1
- Robbins and Cotran Pathologic Basis of Disease
- Kaplan USMLE Step 1 Hematology Lecture Notes
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