The Positive Rate of Autoantibodies in Korean Patients with Connective Tissue Diseases

Choi, Jung Chul; Chang, Sung Eun; Choi, Jee Ho; Sung, Kyung Jeh; Moon, Kee Chan; Koh, Jai Kyoung

Abstract

BACKGROUND: Serologic test is important in the evaluation of patients with connective tissue diseases(CTD). It does help to confirm a clinical diagnosis, classify subsets of CTD and predict prognosis. In Korean patients with various CTD, the positive rate of each autoantibody has not been reported in dermatologic literatures.
OBJECTIVES
The purpose of this study was aimed at investigating the positive rate of autoantibodies in Korean patients with CTD.
PATIENTS AND METHODS
The 173 patients who visited the dermatologic clinic of Asan medical center from 1995 to 2000 were diagnosed as having systemic lupus erythematosus(SLE), discoid lupus erythematosus(DLE), dermatomyositis or scleroderma. Fifty eight patients of SLE, 35 patients of DLE, 34 patients of dermatomyositis and 46 patients of scleroderma were enrolled. Using the sera from the total 173 patients, the presence of antinuclear antibody(ANA) was detected by an indirect immunofluorescence test using cultured human cell substrates(HEp-2 cells). The presence of extractable nuclear antigen(RNP, Sm, Ro(SS-A), La(SS-B), Scl-70, Jo-1) was detected by gel double immunodiffusion. Anti-double-stranded DNA(dsDNA) was detected by radioimmunoassay.
RESULTS
1. Of the 58 patients with SLE, the sera of 56 patients(96%) was positive to ANA. Thirty four patients(58%) had anti-dsDNA antibodies. Thirteen patients(22%) had anti-RNP antibodies. Twenty nine patients(50%) had anti-Ro(SS-A) antibodies while 5 patients(8%) had anti-La(SS-B) antibodies. Only 5 patients(8%) had anti-Sm antibodies. 2. Of the 35 patients with DLE, the sera of 17 patients(48%) was positive to ANA. Among 10 patients tested, only one patient(10%) had anti-RNP antibodies. Two patients(20%) had both anti-Ro(SS-A) and anti-La(SS-B) antibodies. 3. Of the 34 patients with Dermatomyositis, the sera of 16 patients(47%) was positive to ANA. Among 13 patients tested, one patient(7%) had anti-dsDNA antibody. Among 20 patients tested, two patients(10%) had anti-Ro(SS-A) antibodies. Two patients(10%) had anti-Jo-1 antibodies. 4. Of the 46 patients with scleroderma, the sera of 24 patients(52%) was positive to ANA. Among 12 patients tested, two patients(16%) had anti-dsDNA antibodies. Among 30 patients tested, nine patients(30%) had anti-Scl-70 antibodies.
CONCLUSIONS
1. In Korean patients with CTD, the positive rate of various autoantibodies were similar to the previous western reports except some minor differences; (1) lower positive rate of anti-Sm and higher positive rate of anti-Ro(SS-A) in SLE. (2) lower positive rate of anti-Jo-1 in dermatomyositis. (3) higher positive rate of anti-Scl-70 in scleroderma. 2. SLE patients have significantly higher percentage of ANA, anti-dsDNA, anti-RNP, anti-Sm, anti-Ro(SS-A) antibodies in compared to DLE, dermatomyositis, and scleroderma patients.