Cluster of Differentiation 1a (CD1a) is part of a family of major histocompatibility complex (MHC) antigen-like glycoproteins that associate with beta-2-microglobulin. CD1a binds self and non-self lipid and glycolipid antigens, presenting them to T-cell receptors on natural killer T cells. CD1a antibody labels cortical thymocytes, Langerhans' cells and dendritic cells. It has been used to identify Langerhans' cell histiocytosis and precursor T lymphoblastic lymphoma/leukemia.