TLR2 expression is localized to the perivascular region and lining layer. (A) Two representative photomicrograph (Pt 1 and Pt 2) of RA synovial tissue of 10 patients stained for TLR2 expression. Expression is localized to the perivascular region and to the lining layer, with no staining observed for matched 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) RA synovial tissue explant cultures were stimulated with TLR2 angonist Pam3CSK4 at 200 ng, 1 and 10 μg/ml. Levels of IL-6 (n = 11) and IL-8 (n = 8) in the culture supernatants were determined after 24 hrs. Values are expressed as the mean ± SEM. * P < 0.05 significantly different from control as determined using Wilcoxon Signed Rank analysis.