Mieloides

Mieloides, in a biological context, refers to the myeloid lineage, a branch of hematopoietic differentiation in the bone marrow. Myeloid cells derive from hematopoietic stem cells through common myeloid progenitors and include several mature cell types that perform roles in immunity, oxygen transport, and hemostasis. The term is often contrasted with lymphoid, which gives rise to T and B lymphocytes and natural killer cells.

Development of the myeloid compartment begins with hematopoietic stem cells differentiating into common myeloid progenitors (CMPs). CMPs further differentiate into granulocyte–monocyte progenitors (GMPs) and megakaryocyte–erythroid progenitors (MEPs). GMPs give rise to granulocytes (neutrophils, eosinophils, basophils) and monocytes/macrophages, while MEPs produce erythrocytes and platelets. Dendritic cells can also arise from the myeloid lineage. Mature myeloid cells make up a large portion of circulating leukocytes and operate across tissues.

Myeloid cells contribute to innate immunity, inflammation, tissue repair, and hemostasis. Neutrophils act as rapid first responders; monocytes and macrophages phagocytose pathogens and debris and present antigens; dendritic cells link innate and adaptive immunity. Erythrocytes transport oxygen, and platelets mediate clotting and wound healing. Dysregulation of myeloid development or function underlies various disorders, including acute myeloid leukemia, myelodysplastic syndromes, and myeloproliferative neoplasms. In medical classification, the distinction between myeloid and lymphoid lineages informs diagnosis and treatment strategies.