Figure 16: Experimental design and results of assessing β2-AR-mediated changes in IFN-γ production by immune cells from secondary immune organs of arthritic rats. Lewis rats were treated with complete Freund’s adjuvant to induce arthritis on experimental day 0. Disease onset occurs consistently at days 11-12 in the adjuvant induced arthritis model. Joint inflammation peaks at day 21 and then wanes by day 28, however the joint destruction progresses steadily between days 12-28. On days 12 through 28, the β2-AR agonist, terbutaline, or vehicle was administered by intraperitoneal injection. Secondary lymphoid organs (lymph nodes that drain the arthritic hind limbs (DLN), spleen and mesenteric lymph nodes (MLN)) were collected and cell harvested to assess IFN-γ production in vitro. After 24 hours in culture (without additional stimulation), the media was collected and IFN-γ levels were assessed using ELISA methods. In vivo treatment with the β2-AR agonist resulted in an ex vivo increase in DLN cell production of IFN-γ. In contrast, MLN cells produced less IFN-γ. IFN-γ production by spleen cells but was unchanged by β2-AR agonist treatment.