A type I monoclonal antibody identifies a common epitope on multiple isoforms of the pig CD34

T.W. Jensen, D.A. Swanson, L.A. Rund, K. Kim, S.G. Clark-Deener, L.B. Schook
Swine in Biomedical Research Conference, July 17-19, 2011, Chicago, IL


CD34 is an important marker for the identification and enrichment of stem and progenitor cell subsets used in a variety of cell-based therapies but there are no commercial monoclonal antibodies available that cross-react with pig CD34 (pCD34).  We have produced a monoclonal antibody which recognizes multiple isoforms of pig CD34. Balb/c mice were immunized with a fusion protein encompassing the extracellular region of porcine CD34.  After screening a panel of 480 monoclonal antibodies we identified 1 antibody, 3G7, capable of recognizing porcine CD34 expressed in CHO cells, hematopoietic cells, adipose derived stromal vascular cells, and endothelial progenitor cells.  The epitope recognized by 3G7 is sensitive to both glycoprotease and neuramindase treatment, classifying 3G7 as a Type I CD34 antibody.  We have previously identified multiple isoforms of porcine CD34 resulting from multiple single nucleotide polymorphisms in the CD34 gene.  The 3G7 antibody was able to recognize two isoforms of pCD34 differing by 6 amino acids.  Both isoforms had similar sensitivity to both glycoprotease and neurominidase treatment.  Western blot analysis of protein extracts from CD34-expressing CHO cells and enriched CD34+ primary cells demonstrates that pig CD34 expressed in these mammalian cells has an apparent electrophoretic mobility of approximately 100kD.  The Type I 3G7 monoclonal antibody recognizes multiple isoforms of pCD34 providing a robust reagent to identify CD34+ cells in porcine tissues.  This antibody will expand the potential of the swine model for use in preclinical trials of stem cell therapies.