IL6 and rheumatoid arthritis: Taking the same threshold for a positive response as described above, we found that six out of 17 RA patients' PBMC responses secreted IL-6 in response to no epitopes, eight patients' responses to citrullinated aggrecan only, none to citrullinated fibrinogen, none to citrullinated collagen type II only and three patients' responses to > 1 citrullinated epitope.