This MAb reacts with 9-O-acetylated disialosyl group linked to the glycoprotein CD60w. CDw60 is a carbohydrate antigen present on gangliosides, platelets and a subset of CD4+, CD8+ peripheral T-cells, but not on B-cells, monocytes or granulocytes. CDw60 is involved in the co-stimulation of T-cells.