GPI-induced TNF-α and IFN-γ production from arthritic splenocytes in vitro. Spleens were removed from glucose-6-phosphate isomerase (GPI)-immunized DBA/1 mice (on day 8 after immunization), and then single-cell suspensions were prepared. MACS separated CD4+ T cells (1 × 106 cells/ml) were stimulated with 5 μg/ml GPI (or glutathione S-transferase [GST]) and antigen-presenting cells (APCs; 2 × 105 cells/ml, mitomycin treated) for 12 hours. The culture supernatants were collected and concentrations of tumor necrosis factor (TNF)-α, IFN-γ, IL-2, IL-4, IL-5, IL-6, IL-10, and IL-12p70 were measured by cytometric bead array. Data were averages of three independent experiments. Error bars represent ± standard error. *P < 0.05, by Mann-Whitney U-test.