CD68 is a 110 kD glycoprotein, known as macrosialin, belonging to sialomucin family and closely related to the family of acidic, highly glycosylated lysosomal-associated membrane proteins (lamps). CD68 is predominately expressed in cytoplasmic granules of monocytes/macrophages, dendritic cells, and granulocytes. It is one of the useful myeloid cell markers. Further studies have shown that CD68 is also expressed by a subset of hematopoietic progenitors, gamma/deltaT cells, NK cells, LAK cells, subset of B cells, fibroblasts, and endothelial cells. The biological function of CD68 is still unknown.