CLEC5A and rheumatoid arthritis: The results show that MDL-1 activator (DV2-antigen) stimulation on PBMCs induced greater-fold increases of mRNA expression levels of IL-1β (up to ∼53-fold), IL-6 (up to ∼135-fold), IL-17A (up to ∼3.5-fold), and TNF-α (up to ∼4-fold) in active RA patients compared to those in OA patients or healthy subjects, indicating that MDL-1 activation is functional.