Blocking ATP-induced rapid MMP-9 release with antibodies. PBMCs (2 × 10⁷/mL) were incubated 5 minutes with or without anti–hu-TNF-α mAb (1:10 dilution) or anti–IL-1β mAb (2 μg/mL) in NaCl medium containing 0.1 mM CaCl₂, followed by addition of 1 mM ATP (gray bar). Supernatants were collected after 30 minutes. MMP-9 concentrations were measured by ELISA. Results from individuals were normalized and shown as mean ± SEM (n = 4).