ANTIHISTONE AUTOANTIBODIES REACT SPECIFICALLY WITH THE B-CELL SURFACE

In an attempt to induce an immune response against MlS-1a antigens by immunizing C57B1/6 mouse (Mls-1b) with purified B cells from DBA/2 mou se (Mls-1a), we generated a panel of monoclonal antibodies from which the 5B9.6 mAb, taken as a representative antibody, was thoroughly inve stigated. This antibody specifically reacts with B cells from all mous e strains studied including C57B1/6 mice as shown by FACS analysis of double-antibody labelled spleen cells. Using enzyme immunoassays and i mmunoprecipitation techniques, 5B9.6 mAb was found to be specific for histones. Amino acid sequence analysis of a peptide derived from a 5B9 .6-immunoprecipitated polypeptide from DBA/2 B cells showed a 100% hom ology with a sequence within H2B histones. Furthermore, 5B9.6 mAb was able to interact with the cell surface of 7OZ/3 cell line, known as a typical pre-B cell line. The presence of histones can be modulated on the surface of 7OZ/3 cells since this antigen was upregulated after ex posure of these cells to a cocktail of IL-1 and cAMP. Finally, 5B9.6 m Ab was shown to interact with freshly isolated B cells from human peri pheral blood.