Analysis of GPI-specific B cells in an adoptive transfer model of arthritis. (A) Representative flow cytometric analysis from 15 experiments of gated B cells in the GPI-PE tetramer and C5a-PE*AF647 tetramer-enriched fraction of Tcra^−/− B6.I-A^b/g7 mice with and without adoptive transfer of GPI-specific CD4⁺ helper T cells (KRN) 7 d before analysis. (B) Combined data from 15 experiments showing the number of GPI tetramer⁺ B cells in individual HEL-specific MD4 Rag1^−/−, B6.I-A^b/g7, Tcra^−/− B6.I-A^b/g7, and Tcra^−/− B6.I-A^b/g7 mice 7 d after transfer of KRN cells. The line indicates the mean (n = 3–26). (C) Combined data from three experiments showing the number of GPI tetramer⁺ B cells of each subpopulation identified as shown in Fig. 3. (D) Combined data from four experiments showing the percentage of GPI Tetramer⁺ B cells recovered in the presence of monomeric GPI or OVA competitor as compared with the number of cells detected in a sample in which no competitor antigen was added. Each data point represents the mean ± SEM (n = 5). (E, left) Pooled data from 2 experiments showing the arthritis clinical disease activity scores (max = 12) of individual Tcra^−/− B6.I-A^b/g7 mice (n = 4) and (right) mean (n = 5; ± SEM) serum anti-GPI IgG1 measured on the days indicated after adoptive transfer of KRN CD4⁺ helper T cells. Serum anti-GPI IgG1 antibody levels reflect the optical density measured at 1:900 dilution of serum. (F) Representative flow cytometric analysis from 5 experiments showing GL7 and intracellular Ig expression on gated GPI tetramer⁺ B cells 7 d after transfer of KRN cells. (G) Representative flow cytometric analysis from 3 experiments showing surface IgG1 expression on GL7⁺ and intracellular Ig^HI GPI tetramer⁺ populations 7 d after transfer of KRN cells. (H) Pooled data from 3 experiments showing the arthritis clinical disease activity scores (max = 12) 12 d after the transfer of KRN CD4⁺ helper T cells into NOD Rag1^−/− IL2rγ^−/− recipient mice that received FACS-purified GPI tetramer⁺ or C5a tetramer⁺ B cells. Each data point indicates an individual mouse (n = 5–7), and the bar indicates the mean. The p-values were established using an unpaired two-tailed Student’s t test. (I) Arthritis clinical disease activity scores from the recipients of GPI tetramer⁺ B cells from H plotted against the total number of GPI tetramer⁺ B cells in the recipient animals 12 d after the transfer of KRN CD4⁺ helper T cells.