Class II HLA molecules are glycoproteins expressed primarily on the surface of Antigen-Presenting Cells (APCs) such as dendritic cells, B lymphocytes, and macrophages. They are composed of two polypeptide chains, alpha and beta, which form a heterodimer. These molecules are specialized for presenting exogenous antigens that have been processed and loaded onto the HLA molecule within the endosomal/lysosomal compartments.
