Antihistone antibodies detected by micro-ELISA and immunoblotting in mice with lupus-like syndrome (MRL/1, MRL/n, PN, and NZB strains).

Antihistone antibodies were searched for in autoimmune prone strains of mice: MRL/1, MRL/n, PN, and NZB by micro-enzyme-linked immunosorbent assay (micro-ELISA with total histones or H1 fraction as antigen) and immunoblotting using a solution of total histones containing H1, H2A, H2B, H3, and H4. In addition, we specified the localization of H1 fraction epitopes recognized by mouse anti-H1 autoantibodies using immunoblotting with H1 digested by alpha-1-chymotrypsin. All strains of autoimmune mice synthesize antihistone antibodies, principally MRL/1, then MRL/n and PN, and finally NZB. Among MRL/1 mice, the histone fractions best recognized by antihistone antibodies, are, in decreasing order: H1, H3, H4, H2B, and H2A. With MRL/n and, even more strikingly with PN mice, the antihistone antibodies recognize preferentially H1 and H2B as they do in human lupus. Finally, the binding of antihistone antibodies from NZB mice is slightly stronger for H2B than for the other histone fractions. The anti-H1 autoantibodies from MRL/1, MRL/n, and PN mice are mainly directed at epitopes located on the C terminal of the histone molecule.