CD34 (Precursor Cell Marker), in Visit Clinic

CD34 is a cell surface glycoprotein marker chiefly expressed on hematopoietic stem and progenitor cells, including those in bone marrow and umbilical cord blood. It also marks endothelial and endothelial progenitor cells, certain vascular-associated cells, and some dendritic cell subsets. Clinically, CD34 is used to identify, isolate, and quantify stem/progenitor cells for transplantation and research.

CD34 positive means cells express the CD34 surface antigen, marking hematopoietic stem and progenitor cells and some endothelial cells. Detection by flow cytometry or immunohistochemistry indicates cellular immaturity or stem-cell characteristics, used to diagnose certain leukemias, quantify stem-cell collections for transplant, and isolate progenitor cells. CD34 status can inform prognosis and treatment choices depending on the clinical context.

CD150 (SLAMF1) is a cell-surface receptor used as a marker to identify and isolate hematopoietic stem cells—especially long-term HSCs in research—while also being expressed on activated immune cells (T and B lymphocytes, macrophages, dendritic cells). It participates in immune cell activation and signaling and can act as a receptor for measles virus.

CD34-positive cells express the CD34 surface protein—mainly hematopoietic stem/progenitor cells and some endothelial progenitors—used to identify and quantify stem cells for transplantation and recovery monitoring. CD34-negative cells lack this marker, representing more differentiated blood cells and many non-hematopoietic cell types. Clinically, CD34 testing guides stem cell collection, transplant decisions, and certain hematology diagnostics.

Almost everyone carries CD34‑positive cells: they are markers on hematopoietic stem/progenitor cells (mainly in bone marrow), endothelial progenitors and some tissue progenitors. Peripheral blood levels are normally low but rise with age, illness, or after mobilizing treatments. Rare conditions (severe bone marrow failure or certain therapies) can markedly reduce or nearly eliminate detectable CD34+ cells.

Another name for CD34 is the hematopoietic progenitor cell antigen (HPCA‑1). CD34 is a transmembrane sialomucin‑like glycoprotein expressed on early haematopoietic and endothelial progenitor cells; it’s often referred to as the CD34 antigen or haematopoietic stem/progenitor cell marker used to identify and isolate stem cells in clinical and research settings.