Biochemical and antigenic characterization of CD45 polypeptides expressed on plasma membrane and internal granules of human neutrophils

AbstractThe expression of CD45 polypeptides, a phosphotyrosine phosphatase complex specific of leukocytes, has been investigated in both resting and activated neutrophils by using anti-CD45 monoclonal antibodies (MAb) which specifically recognize different polypeptide components of the CD45 molecular complex. Polypeptides of 180 and 130–150 kDa were equally precipitated by either a conventional CD45 MAb recognizing an antigenic determinant shared by the four CD45 glycoproteins (220, 205, 190 and 180 kDa) or by the anti-180 kDa UCHL1 MAb. These polypeptides were overexpressed on neutrophil plasma membranes after degranulatory stimulation. Conversely, neither the anti-220 kDa CD45R nor anti-220/205/190 kDa MAb reacted with CD45 molecules from resting or activated neutrophils. Furthermore, permeabilization analysis and comparative immunoprecipitation studies with different anti-CD45 MAb from fractions enriched in various neutrophil granules revealed that CD45 polypeptides (180 and 130–150 kDa) from internal granules are antigenic and biochemically identical to those expressed on plasma membrane