Figure 5: Circulating IgM concentration is suppressed early after stroke in patients.

(a) Comparison of log-transformed plasma IgM concentrations shows a significantly reduced mean IgM concentration in patients at admission (up to 12 h after onset of stroke symptoms), 24 h and 5–7 days after stroke in comparison to paired controls. To control for circadian variation, stroke samples taken at admission and 24 h were compared to paired admission controls, and stroke samples taken at 5–7 days were compared to 09:00 hours paired controls (n=38). (b) Minimum IgM concentration measured in the first 7 day after stroke, was significantly lower in stroke patients who developed infection within 14 days after stroke onset than in those who did not (+ infection n=12, − infection n=23). (c) Average stroke severity on presentation, as measured by National Institute of Health Stroke Scale (NIHSS) was significantly higher in patients who developed infection within 14 days post stroke in comparison to those who did not (+ infection n=12, − infection n=23). (d) Analysis of the relationship between minimum IgM concentration measured in the first 7 day after stroke and stroke severity (NIHSS score) highlighted a trend for patients who develop infection within 14 day after stroke to have a combination of higher stroke severity and low minimum IgM concentration. Data show mean±s.d., (a) Paired one-way ANOVA with Bonferroni correction; (b,c) unpaired t-test; *P<0.05, **P<0.01.