SCD5 and vasculitis: One study reported significantly higher soluble CD4 (sCD4) in RA patients with severe vasculitis compared to the group with mild vascular changes, with no differences in serum levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and soluble IL-6 receptor (sIL-6R) among groups with a different capillaroscopic score [35].