Monoclonal antibodies derived from BALB/c mice immunized with apoptotic Jurkat T cells recognize known autoantigens

It has been postulated that post-translational modifications and relocalization of proteins during apoptosis may lead to presentation of these molecules to the immune system in such a way that normal mechanisms of tolerance are bypassed. In the present study, Jurkat cells were induced to undergo apoptosis by treatment with the chemotherapeutic agent Ara-C. BALB/c mice were then immunized with the apoptotic cells and hybridomas were generated. Using an indirect immunofluorescence assay, the monoclonal antibodies produced were screened by flow cytometry for those monoclonal antibodies demonstrating reactivity with permeabilized apoptotic Jurkat cells but not with non-permeabilized normal or apoptotic Jurkat cells. Of 281 monoclonal antibodies, 20 monoclonal antibodies with these properties were selected for further analysis. Using 32P- or 35S-metabolically labelled Jurkat cells, these selected monoclonal antibodies were screened for their ability to recognize autoantigens by immunoprecipitation and Western blotting. Well characterized autoimmune sera were then used to confirm the identity of autoantigens by immunoblotting. We demonstrate that immunization of normal mice with apoptotic Jurkat cells results in the formation of antibodies targeting multiple autoantigens or autoantigen complexes, including Ku, rRNPs, snRNPs and vimentin. These findings are consistent with the hypothesis that apoptosis can contribute to the development of autoimmunity.