DS-MB-00482 recognizes human CD200R, a cell surface glycoprotein (also known as OX2R). In humans CD200R is expressed primarily by peripheral blood monocytes and neutrophils but also by other leucocytes including T-lymphocytes and mast cells (1). Studies suggest that CD200-CD200R interaction may be involved in the control of myeloid cellular function. Levels of expression on resting peripheral blood cells are relatively low.