The Mouse monoclonal antibody recognizes CD1b, a 44kDa type I glycoprotein associated with beta2-microglobulin (Workshop IV; Code T015). It is expressed on dendritic cells, Langerhans cells, thymocytes, and T acute lymphoblastic leukemia cells. The CD1 multigene family encodes five forms of the CD1 T-cell surface glycoprotein in human, designated CD1A, 1B, 1C, 1D and 1E. CD1, a type 1 membrane protein, has structural similarity to the MHC class I antigen and has been shown to present lipid antigens for recognition by T lymphocytes. Constitutive endocytosis of CD1B molecules and the differential sorting of MHC class II from lysosomes separate peptide- and lipid antigen-presenting molecules during dendritic cell maturation. CD1B is also expressed in interdigitating cells.