The lupus erythematosus cell phenomenon - Comparative analysis of antichromatin antibody specificity in lupus erythematosus cell-positive and -negative sera

Objective. To compare and investigate antihistone and antichromatin antibod y responses as well as clinical variables in patients with systemic lupus e rythematosus (SLE) who were either positive (LEC+) or negative (LEC-) for t he lupus erythematosus (LE) cell phenomenon. Methods, The binding properties of LEC+ and LEC- SLE sera to chromatin-asso ciated nuclear antigens (histones H1, H2A, H2B, H3, H4; complexes of H2A-H2 B, [H2A-H2B]-DNA, H1-DNA; total and H1-stripped chromatin; native and denat ured DNA) were investigated. In addition, sera from patients with drug-indu ced lupus (by procainamide, hydralazine, or quinidine), as well as from pat ients with rheumatoid arthritis and osteoarthritis, were assessed. Enzyme-l inked immunosorbent assay was used to detect specific antibody binding. Results, Mirroring the important role of histone H1 in the formation of LE cells, anti-histone I-Il reactivity was 8-fold higher in LEC+ sera than in LEC- sera. In addition, reactivities to most of the other antigens tested, i.e., other histones and histone-DNA complexes as well as chromatin and DNA , were significantly higher in LEC+ sera than in LEC- sera. All but 1 serum sample from the patients with drug-induced lupus were negative for LE cell formation as well as for anti-histone H1 reactivity, but displayed high an tibody reactivities to histone-DNA complexes, including chromatin, Sera fro m patients with rheumatoid arthritis and osteoarthritis did not show signif icant binding to these antigens, When comparing the clinical features of LE C+ and LEC- SLE patients, severe organ involvement, including nephritis and central nervous system involvement, was common in the LEC+ group, but rare in the LEC- group. Conclusion. A positive LE cell phenomenon not only correlated with the pres ence of high anti-histone H1 antibody levels in SLE but also indicated sero logically and clinically active disease,vith major organ involvement.