CD34CD38

CD34CD38 refers to the co-expression pattern of two cell-surface markers, CD34 and CD38, on hematopoietic cells. It is a descriptive phenotype used in flow cytometry to identify and sort subsets of hematopoietic stem and progenitor cells from sources such as bone marrow, peripheral blood, and cord blood. The term does not designate a single protein or gene, but rather a marker combination used to distinguish stages within hematopoietic differentiation.

CD34 is a sialomucin-like transmembrane glycoprotein expressed on hematopoietic stem and progenitor cells and, to a lesser extent, on endothelial cells. It has been widely used as a marker to enrich stem cell populations for research and clinical applications, including transplantation. CD34 expression helps identify cells capable of long-term reconstitution in repopulation assays and in clinical stem cell grafts.

CD38 is a type II transmembrane glycoprotein involved in cell signaling and adhesion, with enzymatic activity related to NAD metabolism. In hematopoietic cells, CD38 expression generally increases with maturation and activation, so its presence helps separate more differentiated progenitors (CD34+CD38+) from primitive stem cells (CD34+CD38−).

In hematopoietic biology, CD34+CD38− cells are regarded as the most primitive stem cells with long-term, multilineage repopulating potential, whereas CD34+CD38+ cells are more committed progenitors. In clinical and research settings, CD34 is commonly used to isolate stem cells for transplantation and to study stem/progenitor cell biology. Marker expression can vary with disease status and sample source, so interpretations should consider context. See also CD34 and CD38.