ANTIGEN-SPECIFICITY OF ANTIHISTONE ANTIBODIES IN SYSTEMIC-SCLEROSIS

Objectives-The aim of the study was to determine the prevalence and cl inical significance of antibodies to individual histone components in systemic sclerosis (SSc). Methods-Serum samples from patients with lim ited cutaneous SSc (1SSc; n=42) and diffuse cutaneous SSc (dSSc; n=28) were examined for IgG and/or IgM antibodies to individual histone com ponents and complexes by enzyme linked immunosorbent assay (ELISA). Re sults-The level of IgG antibody to total histones was significantly hi gher in 1SSc and dSSc than in normal controls. The level of IgM antibo dy to total histones was significantly higher in ISSc, but not in dSSc , than in normal controls. IgG antibody to total histones tended to be increased in dSSc when compared with that in ISSc. On the other hand, IgM antibody to total histones tended to be increased in ISSc when co mpared with that in dSSc. Although SSc showed various antihistone spec ificities, H2B, H2A-H2B, (H2A-H2B)-dsDNA were main antigens recognised by IgG antibodies in both 1SSc and dSSc. Although IgM antibodies to H 2B and H2A-H2B were also detected in both ISSc and dSSc, serum samples from 1SSc patients exhibited highest IgM reactivity with H1. Conclusi on-SSc may be included among conditions in which heterogeneous antihis tone antibodies are produced. IgM antibodies to the most accessible hi stone H1 may be related to mild clinical features (ISSc) and IgG antib odies to the inner core molecules of native histone such as H2B or com plexes including H2B may be associated with severe clinical features ( dSSc) in Ssc.