We aimed to examine the levels of serum H4 and activated protein C (APC) in rheumatoid arthritis (RA) and other autoimmune conditions, and investigate the associations between H4 or APC levels and disease activity indicators in RA.
Serum H4 and APC distribution was examined in samples from patients with RA, systemic lupus erythematosus (SLE), polymyositis (PM), and ankylosing spondylitis (AS), as well as in samples from healthy controls, using commercial ELISA kits. Associations of serum H4 or APC levels with disease variables in patients with RA were evaluated. Receiver operating characteristic (ROC) curve analysis was performed to assess the discriminant capacity of APC against RA and non-RA.
The patients with RA, PM, and AS showed higher serum levels of H4 and APC than those from the healthy control individuals, while the SLE patients showed higher serum levels of APC only. Moderate positive correlations between H4 levels and absolute neutrophil count (ANC), platelet count (PLT), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), brinogen (FIB), D-dimer (DD), and complement fraction 3 (C3) were observed. Positive correlations between APC levels and PLT, RF, DD, or DAS28 were additionally found. ROC curve analysis revealed that APC discriminated well between RA and non-RA.
H4 and APC concentrations are elevated in patients with chronic in ammatory autoimmune diseases. The observed associations between H4 and APC and disease variables in patients with RA support a role for H4 and APC in the in ammatory process of the disease.