CD34 (EP88)
Anti-CD34 recognizes a cell surface antigen of approximately 110 kD that is expressed selectively on human hematopoietic progenitor cells, including myeloid and lymphoid lineage progenitors.1 It is a marker of choice for identifying and counting the blasts in leukemia.1 In addition, this marker is expressed by some soft tissue tumors, such as solitary fibrous tumor and gastrointestinal stromal tumor.2 CD34 expression is also found in vascular endothelium.3 Additionally, it appears that proliferating endothelial cells express this molecule in greater amounts than non-proliferating endothelial cells.3 Anti-CD34 labels greater than 85% of angiosarcoma3 and Kaposi’s sarcoma4, but shows low specificity.