Myeloiden

Myeloiden is a term used to describe cells or tissues derived from the myeloid lineage, a branch of hematopoiesis that occurs primarily in the bone marrow. The term comes from Greek mys "myelos" meaning marrow, and -oid meaning "like" or "resembling." In humans, myeloid cells arise from hematopoietic stem cells through myeloid progenitor cells, and are distinguished from the lymphoid lineage.

The myeloid lineage gives rise to erythrocytes (red blood cells), platelets (from megakaryocytes), and several leukocyte types: granulocytes (neutrophils, eosinophils, basophils), monocytes, macrophages, and dendritic cells. Each subset has distinct roles in innate and adaptive immunity and tissue homeostasis. Erythrocytes transport oxygen; platelets mediate clotting and wound repair. Neutrophils provide rapid phagocytosis and antimicrobial substances. Monocytes circulate in blood and differentiate into macrophages or dendritic cells in tissues, where they phagocytose pathogens and present antigens. Dendritic cells are potent antigen-presenting cells bridging innate and adaptive immunity.

In clinical contexts, myeloid-related disorders include myelodysplastic syndromes, myeloproliferative neoplasms, and acute or chronic myeloid leukemias, which arise from malignant transformation of myeloid progenitors. Myeloid cells can also contribute to inflammatory conditions and cancer through processes such as tumor-associated macrophage activity and myeloid-derived suppressor cells.

Thus, myeloiden refers to the family of cells formed from the myeloid lineage, distinct from lymphoid-derived cells such as B and T lymphocytes.