IgG2b is the dominant anti-GPI isotype in mice transferred with Th17 polarized KRN T cells while IgG1 is dominant in mice transferred with naive T cells and KRN/T-bet−/− Th17 cells. Serum titers of individual isotypes of anti-GPI were measured every 7 days by ELISA using isotype-specific secondary antibodies. a, Antibody titers of 10 mice transferred with 9.5×106 Th17 polarized KRN T cells. Each symbol represents one mouse. b, Antibody titers of 9 mice transferred with 3.5×105 naive KRN T cells. c, Antibody titers of 13 mice transferred with 9.5×106 Th17 polarized T cells from KRN/T-bet−/− mice on day 14 post transfer. d, The thickness of both rear ankles was measured as an induction of arthritis in Balb/c mice transferred with Th17 serum or Th17 serum depleted of IgG1. e, Mice were examined for disease severity and given a clinical score of disease. Results are representative of 5 mice per group.