Heterogeneity of the human transferrin receptor and use of anti‐transferrin receptor antibodies to detect tumours in vivo

The human transferrin receptor (TFR) which is present on dividing cells, many tumours and erythroid precursors is readily identified using specific monoclonal antibodies. A new anti-human TFR monoclonal antibody, HuLy-m9, is described and its distribution on cell lines, normal and tumour tissue was examined and compared with two other anti-TFR monoclonal antibodies, namely, OKT9 and 5E9. The three antibodies were shown to recognise different epitopes on the surface of the TFR and have different reactivities with in vitro cell lines. Peptide map analyses of the TFR recognised by each monoclonal antibody from the same cell line were identical; however, differences were observed between cell lines. 131I-radiolabelled HuLy-m9 was used to successfully localise a nasopharyngeal carcinoma in vivo.