Monoclonal Antibodies to Murine Interferon-γ: Affinity Purification and Molecular Characterization of Murine Interferon-γ

Monoclonal antibodies (MAb), AN-18.17.24, obtained by fusing the murine myeloma cell line Ag8.653 with spleen cells from rats immunized with murine interferon gamma (IFNγ) produced by the phorbol myristic acetate(PMA)-stimulated T-cell lymphoma L12-R4, were shown to be specific for MuIFN-γ. An immunoadsorbent column was prepared and used for large-scale purification of MuIFN-γ produced either by PMA-stimulated L12-R4 cells or by normal T-lymphocytes stimulated with Con A and interleukin 2. The purified product from L12-R4 cells, which retained biologic activity, was made up of two proteins (M_r = 16,500 and 17,500) as determined by sodium dodecyl sulfate gel electrophoresis. By contrast MuIFN-γ produced by normal T-lymphocytes resulted in two proteins with Mr of 20,600 and 21,800 as determined by sodium dodecyl sulfate gel electrophoresis. These results indicate that MuIFN-γ produced by L12-R4 tumor cells or by normal Tlymphocytes differ in their molecular weight, probably because of different degrees of glycosylation of the same molecule.