This antibody recognizes a single chain glycoprotein of 105/120 kDa, identified as CD30/Ki-1. Its epitope is located between aa112-412. CD30 is synthesized as a 90 kDa precursor, which is processed in the Golgi complex into a membrane-bound phosphorylated mature 105/120 kDa glycoprotein. In Hodgkin’s disease, CD30/Ki-1 antigen is expressed by mononuclear-Hodgkin and multinucleated Reed-Sternberg cells. It is also expressed by the tumor cells of a majority of anaplastic large cell lymphomas as well as by a varying proportion of activated T and B cells. This MAb distinguishes large cell lymphomas derived from activated lymphoid cells from histiocytic malignancies and lymphomas derived from resting and precursor lymphoid cells or from anaplastic carcinomas. About one third of the Ki-1 positive lymphomas lack the leukocyte common antigen (CD45).