Clinical significance of anti-Scl-70 antibody estimation in pediatric patients with systemic lupus erythematosus

Abstract

Background: Some patients with scleroderma have overlap features with systemic lupus erythematosus (SLE). Anti-Scl-70 antibody was reported in as many as 35% of patients with scleroderma and signifies an increased risk for the development of pulmonary fibrosis and pulmonary hypertension. This antibody was detected in 25% of adult patients with SLE. Objective: We hypothesized that a particular subset of lupus patients might be at an increased risk of certain complications if anti-Scl-70 antibody was elevated in their sera. Methods: Serum anti-Scl-70 antibody levels were assayed by ELISA from 34 pediatric patients with SLE and from 24 healthy controls. Patients were also subjected to clinical evaluation for system involvement and for disease activity by systemic lupus erythematosus disease activity index (SLEDAI). The ESR, serum anti DNA antibody, serum complement 3, creatinine clearance and 24 hours urinary protein excretion were assessed and renal biopsy for histopathology was performed in selected cases. Results: Anti Scl-70 antibody was elevated (> 25 U/ml) in 6 SLE patients (18%), borderline (15-25 U/ml) in 17 patients (50%) and normal (< 15 U/ml) in 11 of them (32%). The patient group had significant elevation of serum anti-Scl-70 antibody levels (mean [SD] = 32.5 [8.8] U/ml) as compared to the controls, (mean [SD]= 9.3 [4.1] U/ml; p < 0.001). Patients with clinical lupus nephritis had significant higher levels of this autoantibody as compared to those without clinically evident renal involvement. Also, pulmonary hypertension was found significantly related to the high serum levels of anti-Scl-70 antibody. A significant positive correlation could link anti-Scl-70 levels to the ESR values and SLEDAI scores. Anti-Scl-70 levels were neither affected by the presence of neuropsychiatric involvement nor by intake of cytotoxic drugs. Conclusion: Anti-Scl-70 antibody is present in a significant subset of patients with SLE. For this subset, it offers a good correlate of disease activity and suggests an increased risk for pulmonary hypertension and renal involvement.

Keywords: SLE; anti-Scl-70; pulmonary hypertension; lupus nephritis; SLEDAI

Egypt J Pediatr Allergy Immunol 2006; 4(2): 53-60.