The production of type 1 cytokines by PBMC from matched triplets of RA, CA and control subjects in response to a range of stimuli i.e. mouse anti-human CD3 (OKT3) 1 μg/ml, LPS 1 μg/ml and heat killed S. aureus Cowan strain 1 (0.01%w/v) (SAC). (A) IL-12 production at 72 h, (B) IFN-γ production at 24 h, (C) TNF-α production at 24 h. A similar profile of results were obtained when IL-12 was assayed at 24 h (data not shown). All supernatant samples were assayed in parallel by ELISA. Each point denotes the result from individual supernatants or from multiple identical values. Bar denotes median value for the group. RA values were significantly lower than those in the CA group under the following conditions: For IL-12 (A) media alone, OKT3, LPS, For IFN-γ(B) OKT3, for TNF-α (C) Media alone OKT3, LPS.