Figure 6.

Circulating specific IgG antibodies to immunogenic commensal species are raised in CD but not UC donors. A: Plasma was assayed for IgG antibodies using a coating assay. Ratios of median fluorescence intensity of anti-IgG-stained vs isotype control for each sample are shown [median and 95% CIs]. Kruskal–Wallis tests were used to compare groups; n = 30 HC, n = 18 CD and UC. B: Correlation of B cell proliferative responses to E. coli against circulating IgG in 40 matched donors, including Pearson correlation coefficient. Correlations with other species were not significant. C: Antibodies against non-enteric viruses in health vs IBD. Plasma were assayed by ELISA for IgG to viral antigens and results expressed in arbitrary units. Grey lines represent cut-off points below which titres are considered negative. One-way ANOVA was used to compare groups. IBD,inflammatory bowel disease; HC, healthy controls; CD, Crohn’s disease; UC, ulcerative colitis; CI, confidence interval.