Net cytokine secretion by peripheral blood mononuclear cells stimulated with citrullinated and native peptides. Net TNF, IFNγ, IL-10 and IL-17 secretion by peripheral blood mononuclear cells from 17 rheumatoid arthritis (RA) patients and six healthy controls incubated with 0, 3 or 30 μg/ml citrullinated (cit) and native peptides as shown. Cytokines were assessed in supernatants by the BD Cytometric Bead Array. Net cytokine secretion was calculated as in Figure 2B. Each dot represents one individual. *P < 0.05, comparing IL-10 responses with citrullinated and native aggrecan (Mann-Whitney test).