The XX sex chromosome complement, as compared with the XY⁻, confers greater disease severity to adoptive EAE. (A) Effect of sex chromosome complement on adoptive EAE. LNCs from ovariectomized female XX and XY⁻ mice (immunized with PLP 139–151) were adoptively transferred into WT females (gonadally intact). Mean clinical disease course was significantly higher in recipients of LNCs derived from XX mice as compared with those derived from XY⁻ mice. P < 0.0001. XX, •, n = 13; XY⁻, ▴, n = 8. Data are representative of two independent experiments. Graph shows mean clinical score for each group at each time point. Statistical analysis compares mean score for all days from each group. (B) Recipients of XX-derived LNCs had more CNS inflammation than recipients of XY⁻-derived LNCs. Shown are representative thoracic spinal cord sections of mice with adoptively transferred EAE that were coimmunostained with anti-CD45 (red) and anti–β3-tubulin (green) antibodies. LF, lateral funiculus; VH, ventral horn). EAE mice that received LNCs derived from XX mice (left) had significantly increased CD45⁺ staining as compared with EAE mice that received LNCs derived from XY⁻ mice (right). Bar, 100 μm. (C) Quantification of EAE neuropathology. Mice that received XX LNCs had a significant increase in CD45⁺ cells compared with mice that received XY⁻ LNCs. P < 0.001, Student's t test. XX, •, n = 12; XY⁻, ▴, n = 12. Data are representative of two independent experiments. Histograms show the means and the SEM for mice in each group. Female symbol with x overlay indicates ovariectomized female.

The XX sex chromosome complement, as compared with the XY⁻, confers greater disease severity to lupus. (A) Castrated male XXSry and XY⁻Sry SJL mice were injected with pristane and monitored daily for signs of disease. By 26 wk, XXSry mice had increased mortality as compared with XY⁻Sry mice. P = 0.027. XXSry, •, n = 12; XY⁻Sry, ▴, n = 13. (B) Ovariectomized female XX and XY⁻ SJL mice were injected with pristane and monitored daily for signs of disease. At 26 wk, XX mice had increased mortality as compared with XY⁻ mice. P = 0.036. XX, •, n = 13; XY⁻, ▴, n = 15. Data are representative of two independent experiments. (C) Kidneys from ovariectomized female XX and XY⁻ female SJL mice injected with pristane were harvested upon death for renal pathology. Representative renal histology from pristane-induced lupus SJL mice showing that ovariectomized female XX mice (left) have more severe nephritis than ovariectomized female XY⁻ mice (right). GI, glomerular infiltration; GS, segmental glomerulosclerosis; Cr, cellular crescent; TC, tubular casts; TA, tubular atrophy; FSP, focal segmental proliferative; MM, mild mesangial matrix. Bars, 50 μm. (D) Lesions from pristane-injected ovariectomized female XX and XY⁻ mice were scored, ranked, and expressed as the percent frequency of mice in each group. A greater percentage of XX mice showed severe tubular disease scores (≥10; P = 0.006), chronic lesion scores (≥3; P = 0.046), and vascular lesion scores (P = 0.013) than their XY⁻ littermates. In addition, a greater percentage of XX mice showed severe glomerular disease scores (≥10; NS). XX, n = 13; XY⁻, n = 14. XX, white columns; XY⁻, shaded columns. (E) Effect of sex chromosome complement on autoantibody levels in pristane-induced lupus. Ovariectomized female XX and XY⁻ SJL mice were bled to detect anti-dsDNA antibodies in serum. 16 wk after pristane injection, XX mice had significantly higher levels of anti-dsDNA IgG antibody in sera than XY⁻ mice. P < 0.01. XX, n = 9, white columns; XY⁻, n = 9, shaded columns; (NZBxNZW)F1 (+control), diagonal-lined columns; BALB/c (−control), vertical-lined columns. Histograms show the means and the SEM for mice in each group from one of three independent experiments. Female symbol with x overlay indicates ovariectomized female; male symbol with x overlay indicates castrated male.

Effect of sex chromosome complement on IL-13Rα2 expression. Freshly isolated splenocytes from PLP 139–151 immunized SJL mice of the XX or the XY⁻ sex chromosome complement were analyzed for the expression of IL-13Rα2 (top) and IL-13Rα1 (bottom) on B cells (CD19⁺), macrophages (CD11b⁺), dendritic cells (CD11c⁺), and myeloid dendritic cells (CD11c⁺CD11b⁺) by flow cytometry. XX, thick red lines; XY⁻, blue lines; shaded area, negative control. The mean fluorescent intensities are indicated on FACS plots (red, XX; blue, XY⁻). IL-13Rα2 expression was significantly higher on macrophages, dendritic cells, and myeloid dendritic cells in XX mice than in XY⁻ mice. *, P < 0.05; n = 3 each. Results represent two independent experiments.

The XX sex chromosome complement, as compared with the XY⁻, confers greater disease severity to active EAE. (A) Active EAE was induced in castrated XXSry and XY⁻Sry male mice with autoantigen PLP 139–151. Mean clinical disease course was more severe in castrated male XXSry mice as compared with XY⁻Sry mice. P < 0.0001. XXSry, •, n = 6; XY⁻Sry, ▴, n = 5. (B) Active EAE was induced in ovariectomized XX and XY⁻ female mice with autoantigen PLP 139–151. Clinical disease course was more severe in ovariectomized female XX mice compared with XY⁻ mice. P < 0.0001. XX, •, n = 5; XY⁻, ▴, n = 5. Data are representative of one experiment in males and two independent experiments in females. Graphs show mean clinical score for each group at each time point. Statistical analysis compares mean score for all days from each group. Female symbol with x overlay indicates ovariectomized female; male symbol with x overlay indicates castrated male.

No effect of sex chromosome complement for active EAE in C57BL/6 mice. (A) Active EAE was induced in castrated male XXSry and XY⁻Sry C57BL/6 mice with autoantigen MOG 35–55. Mean clinical disease course was no different when comparing castrated male XXSry mice to XY⁻Sry mice. XXSry, •, n = 6; XY⁻Sry, ▴, n = 6. (B) Active EAE was induced in ovariectomized female XX and XY⁻ C57BL/6 mice with autoantigen MOG 35–55. Mean clinical disease course was also no different when comparing ovariectomized female XX versus XY⁻ mice. XX, •, n = 6; XY⁻, ▴, n = 4. Data are representative of three independent experiments in males and two independent experiments in females. Graphs show mean clinical score for each group at each time point. Statistical analysis compares mean score for all days from each group. Female symbol with x overlay indicates ovariectomized female; male symbol with x overlay indicates castrated male.

Effect of sex chromosome complement on Th2 cytokine levels. Ovariectomized female XX and XY⁻ SJL mice were immunized with PLP 139–151, and after 10 d, draining LNCs were stimulated with PLP 139–151 and assessed for cytokine levels in supernatants. IL-13 (top) and IL-5 (middle) were significantly increased in XY⁻ females compared with XX females. *, P < 0.05. XX, •, n = 4; XY⁻, ▴, n = 3. Ovariectomized female XX and XY⁻ SJL mice were injected with pristane, and after 10 d, splenocytes were stimulated with anti-CD3ε/anti-CD28 and cultured for cytokine production. IL-4 levels in supernatant were significantly higher in XY⁻ females as compared with XX females. *, P < 0.05. XX, •, n = 3; XY⁻, ▴, n = 3. All data are representative of at least three independent experiments. Graphs show the means and the SEM of mice in each group for each concentration. Female symbol with x overlay indicates ovariectomized female.