Clone B4B6 recognizes the human CD172b antigen, a single-pass type I membrane protein also known as signal-regulatory protein beta (SIRPβ). SIRPs are a family of transmembrane receptor-like signaling proteins that are abundantly expressed in hematopoietic cells, including granulocytes, monocytes, dendritic cells, and lymphocytes. In addition, SIRPs are expressed in neuronal cells and certain types of cancer cells. SIRPs can be divided into two subfamilies, CD172a and CD172b, based on the putative structures of their C-terminal intracellular domains which distinguish them as either activating (CD172b) or inhibitory (CD172a) isoforms. CD172b is expressed on peripheral blood monocytes, dendritic cells, and granulocytes.
