Anticentromere autoantibodies in patients without Raynaud's disease or systemic sclerosis

Clinical significance of autoantibodies to the pericentromeric heterochromatin protein 1a protein

OBJECTIVE

The objective of the study is to determine the frequency and the clinical significance of autoantibodies to the pericentromeric heterochromatin protein 1 (HP1). So far this antinuclear antibody specificity has been mainly reported in patients with the CREST syndrome.

METHODS

We screened the sera of 199 individuals, including patients suffering from various autoimmune disorders (Group I, n=145) and non autoimmune diseases (Group II, n=44 patients) as well as healthy individuals (Group III, n=30). The sera were systematically tested by Western blot and ELISA using a GST-HP1α fusion protein as an antigen.

RESULTS

Anti-HP1 antibodies were detected in 32% of patients in Group I, 11.3% in Group II and 3.3% of individuals in Group III. They could be detected in sera containing or not antinuclear antibodies detectable by indirect immunofluorescence. Anti-HP1 antibodies were mostly associated with the CREST and Sjogren's syndromes (70% and 44.4%, respectively). They could also be detected in 22.2% of patients suffering from various other autoimmune diseases. However, their negative predictive value was 94% in the CREST syndrome.

CONCLUSION

Anti-HP1 autoantibodies are associated with a large spectrum of disorders. However, they have a diagnostic value in the CREST syndrome.

Incidence and clinical correlation of anticentromere antibody in Thai patients

Anticentromere antibodies (ACA) are useful in assessing and classifying patients with mild variant of systemic sclerosis called calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias (CREST) syndrome. From their prognostic significance, we are interested in the prevalence and disease correlation in Thai patients. A total of 3,233 serum samples of patients with any musculoskeletal symptoms were sent for antinuclear antibody determination at Ramathibodi Immunology Laboratory Service between the years 1998 and 2001. Forty sera (1.23%) were ACA positive. These sera were from 27 patients with autoimmune diseases and 13 with nonautoimmune diseases. Among autoimmune group, scleroderma was the most common diagnosis (33.3%) with limited sclerosis being the most frequent variant. The percentages of autoimmune disease were almost the same among the low-titer (1:40) and the high-titer (1:640) groups. The study suggests that the prevalence of ACA in Thai patients is low. The presence of ACA detected in patients with vague musculoskeletal symptoms does not suggest a diagnosis of CREST syndrome. Even high-titer ACA can be found in nonautoimmune diseases.