CCL13 and systemic sclerosis: Nevertheless, in a cross-sectional study comparing several illnesses, serum CCL13 levels were measured in patients with systemic sclerosis (SSc), dermatomyositis, systemic lupus erythematosus (SLE), and healthy individuals, and it was discovered that only SSc patients had elevated levels of serum CCL13 compared to the control group (58, 59).