To investigate the kinetics of CXCL8 truncation in the presence of synovial fluids of arthritis patients, we exposed exogeneous CXCL8(1-77) to a small volume (20 μL, which is too small to detect endogeneous CXCL8 proteoforms) of synovial fluids from JIA patients (n = 4). Here, CXCL8 is linked to juvenile idiopathic arthritis.