CD15 (Myeloid Cell Marker)

Yes — CD15 (Lewis X) is commonly used as a myeloid marker, particularly for granulocytic cells such as neutrophils and eosinophils, and is often positive in myeloid leukemias. However, it is not entirely specific: some monocytes, certain B‑cell subsets, and Hodgkin/Reed–Sternberg cells can also express CD15, so results need correlation with additional markers.

CD15 (Lewis X) is a carbohydrate cell-surface antigen expressed mainly on neutrophils, eosinophils and monocytes, and on some macrophages and epithelial cells. Clinically it marks granulocytic/myeloid differentiation and is used diagnostically—classically positive in Reed–Sternberg cells of classical Hodgkin lymphoma and in subsets of myeloid leukemias. It also participates in cell adhesion and phagocytic responses.

CD15 is expressed by normal granulocytes/monocytes and by several tumors: classically Reed–Sternberg cells in classical Hodgkin lymphoma; many myeloid neoplasms (some acute myeloid and myelomonocytic leukemias); and a subset of epithelial tumors—particularly adenocarcinomas (colorectal, gastric, pulmonary and others). Occasional non‑Hodgkin lymphomas and reactive inflammatory cells can also be CD15‑positive. It’s used diagnostically in immunohistochemistry.

Myeloid cells typically express CD11b, CD13 and CD33 as core myeloid markers. Monocytes/macrophages show CD14, CD64 and CD68; neutrophils/granulocytes express CD15, CD16 and CD66b. Antigen‑presenting myeloid dendritic cells express HLA‑DR and subsets show CD1c or CD123. CD117 (c‑Kit), CD34 and Fc receptors like CD32 mark progenitors and functional myeloid subsets.

Leukemia immunophenotyping uses CD markers: B‑lineage ALL—CD19, CD10, CD22, CD20; T‑ALL—CD2, CD3, CD5, CD7, CD1a; AML—myeloid markers CD13, CD33, CD117 and MPO, often CD34 on blasts; chronic lymphocytic leukemia—CD19 with aberrant CD5 and CD23 (weak surface Ig); monocytic leukemias show CD14 and CD64. CD45 is used for leukocyte gating. Flow cytometry confirms diagnosis.

No — CD15 (Lewis X) is not typically positive on eosinophils. CD15 is a myeloid/neutrophil-associated antigen used to identify neutrophils and some monocytes. Eosinophils characteristically express different markers (for example IL‑5Rα/CD125, Siglec‑8, CCR3). Occasional reports note weak or variable CD15 staining, but CD15 is not a reliable eosinophil marker.