IL-17 secretion in serum was significantly increased in patients with active SSc (35.9 ± 4.7, n = 13) compared with those with stable SSc (10.5 ± 2.6, P < 0.01, n = 32) and healthy controls (8.1 ± 2.0, P < 0.05, n = 24; Figure 4A). Here, IL17A is linked to systemic sclerosis.