Isolation of a vascular cell wall-specific monoclonal antibody recognizing a cell polarity by using a phage display subtraction method

Using a strategy consisting of (i) the isolation of cell walls from synchronously differentiating cells of Zinnia, (ii) the generation of mAbs with an antibody phage display method, and (iii) screening with a subtraction method, we isolated mAbs recognizing vascular development-specific cell wall components without prior antigen identification. One of the isolated mAbs, designated CN 8, recognized a cell wall component contained in the hemicellulosic fraction. Immunohistochemical analyses showed that the CN 8 epitope was localized to the cell wall of immature tracheary elements and xylem parenchyma cells. In immature tracheary elements, the CN 8 epitope had a polarized localization pattern regardless of whether the cells are formed as parts of vessels in situ or as single tracheary elements in vitro, suggesting that cell polarity autonomously formed on the cell wall may function in tracheary element differentiation.