IL6 and rheumatoid arthritis: For example, in rheumatoid arthritis (RA), a number of studies have reported an increase in serum IL-6 levels in clinically active RA patients (Srirangan and Choy 2010), which can be significantly decreased by effective therapeutic intervention (Madhok et al. 1993), suggesting that IL-6 that is produced in the RA-affected joint may be a primary driver of the progression of RA disease.