Production of a monoclonal antibody (B1N) recognizing human nuclear antigen associated with cell proliferation

This report describes the preliminary characterization of a novel antigen reactive with a murine monoclonal antibody designated B1N produced in our laboratory. This antibody (IgM) reacts in IFI with mammals and also insect cells, by staining in a speckled fashion the nucleus of these cells. Immunoblotting analysis of Hela and murine D55 nuclear extracts revealed a polypeptide with an apparent molecular weight of 120kD (p120). In this work we demonstrated that: 1. this polypeptide appeared in human peripheral blood lymphocytes only when they were induced to proliferate in vitro after phytohemagglutinin stimulation; 2. this polypeptide was no longer detected in D55 resting cells, following serum deprivation; 3. the MAb B1N specifically revealed the nucleus of proliferating cells on frozen sections of uterine tissue. These data strongly suggest that the p120 nuclear antigen expression is associated with the proliferation state of cells.