Table 1.
Characteristics of systemic sclerosis patients with low, intermediate and high serum IL-15 levels
| Characteristic | Low IL-15 level, <0.64 pg/ml (n = 33) | Intermediate IL-15 level, 0.64–0.88 pg/ml (n = 15) | High IL-15 level, >0.88 pg/ml (n = 13) | |||
| Female/male | 29/4 | (88/12) | 11/4 | (73/27) | 10/3 | (77/23) |
| Age at onset (years) | 52 | (45–57) | 48 | (45–54) | 57 | (53–61) |
| Disease duration (months) | 19 | (13–28) | 16 | (11–25) | 11 | (8–21) |
| Clinical features | ||||||
| Skin score (points) | 9 | (4–14) | 11 | (4–17) | 15 | (8–21) |
| Diffuse cutaneous systemic sclerosis/limited cutaneous systemic sclerosis | 8/25 | (24/76) | 3/12 | (20/80) | 6/7 | (46/54) |
| Pitting scars or ulcer | 9 | (27) | 6 | (40) | 3 | (23) |
| Telangiectasis | 9 | (27) | 6 | (40) | 1 | (8) |
| Calcinosis | 6 | (18) | 5 | (33) | 5 | (38) |
| Organ involvement | ||||||
| Oesophagus | 20 | (61) | 11 | (73) | 10 | (77) |
| Lung (radiological) | 7 | (21) | 2 | (13) | 4 | (31) |
| Heart | 5 | (15) | 4 | (27) | 4 | (31) |
| Kidney | 1 | (3) | 1 | (7) | 0 | (0) |
| Muscle | 1 | (3) | 2 | (13) | 1 | (8) |
| Joint | 5 | (15) | 1 | (7) | 0 | (0) |
| Lung function tests | ||||||
| Vital capacity (p%) | 94 | (85–103) | 94 | (84–105) | 75 | (66–89)* |
| Diffusing capacity for carbon monoxide (p%) | 84 | (77–97) | 71 | (60–87)† | 70 | (62–81)‡ |
| Serological findings | ||||||
| Antinuclear antibodies | 21 | (64) | 14 | (93) | 11 | (85) |
| Anti-scleroderma-70 antibodies | 6 | (18) | 4 | (27) | 2 | (15) |
| Anticentromer antibodies | 10 | (30) | 2 | (13) | 2 | (15) |
| Laboratory findings | ||||||
| Erythrocyte sedimentation rate (mm/hour) | 17 | (10–27) | 12 | (8–22) | 12 | (6–18) |
| C-reactive protein (mg/l) | 0 | (0–6) | 0 | (0–8) | 1.6 | (0–8.1) |
| Orosomucoid (g/l) | 0.8 | (0.68–0.91) | 0.86 | (0.77–0.96) | 0.85 | (0.80–1.11) |
| IgG (g/l) | 10.9 | (9.5–14.6) | 9.5 | (7.6–12.2) | 12.6 | (9.6–15.1) |
Data presented as the median (25th and 75th percentiles) or as n (%). Kruskal–Wallis analysis showed P < 0.05 for the vital capacity and diffusing capacity for carbon monoxide. *P < 0.05 for high IL-15 serum level versus low and intermediate IL-15 serum levels; ‡P < 0.05 for high IL-15 serum level versus low IL-15 serum level; †P = 0.057 for intermediate IL-15 serum level versus low IL-15 serum level.