SSc patients with a DAS28-ESR > 3.2 had a statistically significantly higher percentage of peripheral blood CD21low B cells (12.65% of total B cells (IQR: 7.11–13.79) vs. 5.08% of total B cells (IQR: 3.76–7.45), p < 0.01) (Figure 3a), a higher serum IL-4 level (132.98 pg/mL (IQR: 99.12–164.12) vs. 100.80 pg/mL (IQR: 62.78–121.13), p < 0.05) (Figure 3b), and a higher serum IL-21 level (200.77 pg/mL (IQR: 130.13–302.41) vs. 98.83 pg/mL (IQR: 35.70–231.55), p < 0.01) (Figure 3c) compared to SSc patients with a DAS28-ESR ≤ 3.2. Here, IL21 is linked to systemic sclerosis.