Antibodies to Th/To ribonucleoprotein in patients with localized scleroderma

Objective. Antibodies to Th/To ribonucleoprotein (anti-Th/To) have been det ected almost exclusively in patients with systemic sclerosis. Therefore, we aimed to determine the prevalence of anti-Th/To in patients with localized scleroderma. Methods. Seventy serum samples from patients with localized scleroderma wer e examined by RNA immunoprecipitation and indirect immunofluorescence analy sis using HEp-2 cells as substrate. Results. Three (4%) of 70 sera from patients with localized scleroderma imm unoprecipitated 7-2 (Th) RNA and 8-2 (To) RNA. Indirect immunofluorescence analysis demonstrated that all the sera positive for anti-Th/To showed main ly nucleolar staining. In one patient, the coexistence of anti-histone anti body with anti-Th/To was detected by enzyme-linked immunosorbent assay for anti-histone antibody and confirmed using an absorption test with histones followed by indirect immunofluorescence analysis. Moreover, the localized s cleroderma patients with anti-Th/To tended to have significantly fewer scle rotic lesions than those without. Conclusion. Anti-Th/To is one of the serological abnormalities in localized scleroderma, and the presence of anti-Th/To may be a serological indicator of a mild form of cutaneous involvement.