IMMUNOHISTOCHEMICAL LOCALIZATION OF THE MURINE TRANSFERRIN RECEPTOR (TFF) ON BLOOD-TISSUE BARRIERS USING A NOVEL ANTI-TFR MONOCLONAL-ANTIBODY

A novel monoclonal antibody (mAb), 8D3 (IgG2a), that specifically reco gnizes the murine transferrin receptor (TfR) was produced by immunizin g a Lewis rat with a polyoma middle T oncogene-transformed endotheliom a cell line. The 8D3 mAb was obtained by immunohistochemical screening for exclusive staining of vessels forming a blood-brain barrier (BBB) , but not of other vessels. The anti-TfR mAb 8D3 recognizes the TfR al so in FAGS analysis and in western blots and should prove to be useful for affinity purification of the TfR. Whereas 8D3 brightly stains BBB -forming vessels in the central nervous system of mice, it does not st ain the fenestrated capillaries within the choroid plexus and the circ umventricular organs. In testis, where the blood-tissue barrier is loc ated at the level of the Sertoli cells, the 8D3 mAb specifically stain s Sertoli cells but not endothelial cells. Finally, in vitro, 8D3 does not interfere with iron uptake of lymphocytes as it does not influenc e their proliferation. Taken together, 8D3 represents a versatile new tool to study the tissue distribution of the murine TfR and TfR-mediat ed transcytosis across tissue barriers in the mouse.