Production and characterization of murine monoclonal antibodies against human podocalyxin

Podocalyxin (podxl) is a protein with a peptide bone of approximately 55.5 kDa that undergoes a post-translational glycosylation, yielding a final molecular mass from approximately 145 to approximately 200 kDa. This protein is normally found covering the vascular side of the epithelial glomerular cells, the podocytes, and its presence is essential to maintain a normal renal function. It has also been reported in other cells and tissues although its function has not been yet clarified. The carboxy-terminal intracellular domain of podxl is nearly 100% identical in most species; however, the ectodomain shows considerable variations although the cysteine residues are conserved. Detection of this protein is elusive, most likely due to differences in post-translational modifications. We aimed at producing murine monoclonal antibodies against human podxl. Immunization with Chinese hamster ovarian -hpodxl-green fluorescence protein live cells yielded five different monoclonal antibodies that were characterized by enzyme-linked immunosorbent assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis/western blot, flow cytometry, immunohistochemistry, and immunoprecipitation. The different behavior of these antibodies suggests that some of them may react against epitopes masked by different glycosylated protein moieties.