IL6 and Arthritis: S5 Fig shows levels of IL-8, MCP-1, TNF-α, and IL-6 between patients with HSPN without any systemic symptoms other than nephritis and patients with HSPN with arthritis or abdominal symptoms (HSPN-AA). As shown in S5A–S5D Fig, serum levels for IL-8, MCP-1, and IL-6 tended to be higher in patients with HSPN-AA compared to patients with HSPN only although none of the differences showed statistical significance.