Myelo Monocytic Cell Marker : CD 64

CD64 (FcγRI) is a high‑affinity IgG receptor whose expression increases on neutrophils and monocytes/macrophages during acute bacterial infection and systemic inflammation. Clinically, elevated neutrophil CD64 is a sensitive marker of neutrophil activation and correlates with disease severity; it helps detect and monitor bacterial sepsis, distinguish bacterial from viral infection, and guide antibiotic decisions and treatment response.

Yes. Human monocytes express CD64 (FcγRI), with classical (CD14++CD16−) and intermediate (CD14++CD16+) subsets showing high CD64 expression, while non‑classical (CD14+CD16++) monocytes have lower levels. CD64 binds the Fc portion of IgG and is upregulated during infection and inflammation, making it useful for diagnostic and research purposes.

Common CD markers used to identify leukemias include: CD19, CD10, CD22, CD20 (B‑cell ALL/CLL); CD5 and CD23 (CLL); CD3, CD7, CD2 (T‑cell ALL); CD13, CD33, CD117, CD15 (myeloid/AML); and CD34 with HLA‑DR (blast/stem‑cell phenotype). Marker combinations, not single CDs, determine subtype and guide diagnosis and treatment.

Myeloid cells commonly express CD14 (monocytes/macrophages), CD11b and CD33 (myeloid lineage), CD15 and CD66b (granulocytes), CD16 and CD64 (Fc receptors on neutrophils/monocytes/macrophages), CD13 (myeloid progenitors), HLA-DR (antigen-presenting myeloid cells), and CD68 (macrophage marker). These markers are used in flow cytometry and pathology to identify and classify myeloid populations.

Another name for CD64 is Fc gamma receptor I (FcγRI), the high-affinity Fc receptor for IgG. CD64 is expressed mainly on macrophages, monocytes and activated neutrophils, where it binds the Fc portion of IgG antibodies and mediates functions such as antibody-dependent phagocytosis, antigen presentation and immune activation.

Neutrophil CD64 is a sensitive and specific biomarker for bacterial infection and sepsis: expression rises rapidly on neutrophils during bacterial inflammation and often correlates with severity. It can aid early diagnosis, guide antibiotic decisions, and monitor response to therapy. Limitations include requirement for flow cytometry, variable cutoff values, and possible false signals in certain inflammatory or hematologic conditions, so it complements clinical assessment.