OPN301 inhibition of spontaneous cytokine release is comparable to that observed for Adalimumab. (A) One representative image of OPN301 penetration of RA synovial explant cultures of four RA patients. OPN301 was localized to the perivascular and lining layer regions with no staining observed for IgG control. The bar on the lower right hand corner of each photomicrograph represents a distance of 100 μm on the top panel and 50 μm on the bottom panel. (B) OPN301 (1 μg/ml) inhibited spontaneous cytokine release from RA synovial explant cultures (n = 13) and effect that was comparable to that observed anti-TNFα mAb Adalimumab (Hum, 1 μg/ml). Results are expressed as mean ± SEM. * P < 0.05 and ** P < 0.001 significantly different from control as determined using Wilcoxon Signed Rank analysis.