TC686 allows simultaneous detection and enumeration of CD33, CD34 and CD117-positive cells. CD33 is expressed by subsets of myeloid progenitors, monocytes, granulocytic precursors, and at low levels by neutrophils. CD33 has been found on the cell surface of leukemic blasts from the vast majority of cases of acute myeloid leukemia (AML). CD34 expression is confined to lymphohematopoietic progenitor cells, with the exception of capillary endothelial cells. CD34 appears to be expressed at the highest levels on the earliest progenitors, and to decrease progressively with maturation. Approximately 60% of acute B-lymphoid leukemias, 40% of AML and 1-5% of acute T-lymphoid leukemias express CD34. CD117 is a marker for hematopoietic stem and progenitor cells, and tissue mast cells. The majority (50-70%) of CD117-positive cells co-express CD34 and comprise progenitor cells and their precursors of all hematopoietic lineages. CD117 is frequently found to be expressed on blasts of patients with AML, but is absent from ALL blasts.

Recommended control reagent is Dako Code X0978.