CD74 is a type II transmembrane protein which binds to the peptide binding groove of newly synthesized MHC class II alpha/beta heterodimers and prevents their premature association with endogenous polypeptides. CD74 is expressed primarily by antigen presenting cells, such as B-lymphocytes (from before the pre-B cell stage to before the plasma cell stage), macrophages, and monocytes, and many epithelial cells. CD74 antibody stains predominantly germinal center lymphocytes and B-cell lymphomas, but rarely T-cell lymphomas. antibody to CD74 has been shown to be useful in differentiating atypical fibroxanthoma (-) from malignant fibrous histiocytoma (+).

Store the CD74 antibody at 2-8°C (with azide) or aliquot and store at -20°C or colder (without azide).