The clinical relevance of serum antinuclear antibodies in Japanese patients with systemic sclerosis

BACKGROUND: Systemic sclerosis (SSc) is a connective tissue disorder with excessive fibrosis of the skin and various internal organs. Although SSc is a heterogeneous disease, it has been reported that the particular antinuclear antibodies (ANA) are often indicative of clinical features, disease course and overall severity. OBJECTIVE: To clarify the association of clinical and prognostic features with serum ANA in Japanese patients with SSc. METHODS: We studied 203 Japanese patients diagnosed with SSc, who visited our hospital during the period 1983–2005. Six SSc-related ANA were identified using indirect immunofluorescence, double immunodiffusion and immunoprecipitation assays. RESULTS: Patients with SSc were classified into six ANA-based subgroups and a group without ANA. As expected, antitopoisomerase I antibody (Ab, n = 64), anti-RNA polymerases (RNAP) Ab (n = 12) and anti-U3 RNP Ab (n = 5) were associated with diffuse cutaneous SSc, whereas anticentromere Ab (ACA, n = 75), anti-Th/To Ab (n = 7) and anti-U1 RNP Ab (n = 10) were frequently detected in patients with limited cutaneous SSc. Clinical features of the ANA-negative group (n = 10) were heterogeneous. Consistent with previous findings in Caucasian and/or black African patients, antitopoisomerase I Ab was associated with the involvement of vascular and pulmonary fibrosis, leading to decreased survival rate. However, no patients with anti-RNAP Ab developed renal crisis and the frequency of isolated pulmonary hypertension in patients with ACA, anti-Th/To Ab or anti-U3 RNP Ab was similar to that in other ANA-based subgroups. CONCLUSION: These results indicate that the clinical relevance of SSc-related ANA in Japanese patients differs in some aspects from that in Caucasian and/or black African patients.