CD40LG and rheumatoid arthritis: Although we could not detect a correlation between ACPA and P-selectin expression on platelets in all patients with RA (Additional file 2: Figure S2a), we did observe a strong correlation between patients with higher ACPA levels (>1000 AU/ml) and the expression of both P-selectin (Fig. 1g) (Pearson’s r=0.6289, P<0.01) and the production of sCD40L by platelets (Fig. 1h) (Pearson’s r=0.6751, P<0.01).