Specificity:Recognizes an epitope within the class II MHC complex. In normal tissue identifies dendritic cells and a proportion of B lymphocytes. Within the macrophage/dendritic cell populations the epitope seen by RFD1 is co-expressed with RFD7 by a subset of cells that exhibit suppressive activity on T cell stimulation. It will not bind to monocytes or any cells within the granulocyte series. Species Crossreactivity: macaque