Mouse monoclonal antibody conjugated to PE which recognizes HLA-DR that belongs to the MHC class II family. It localized in endoplasmic reticulum membrane, golgi apparatus. It binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC). HLA-DR is a heterodimeric transmembrane protein composed of alpha and beta subunits and plays an important role in the presentation of peptides to CD4+ T lymphocytes.