CX3CL1 and infection: There were no statistically significant differences in levels of fractalkine on day 4-post infection compared to baseline in any subject group (non-asthmatics (n = 10) baseline median 58.50, day 4 60.85, P>0.999; mild asthmatics (n = 11) baseline median 63.80, day 4 61.00, P = 0.520; moderate asthmatics (n = 14) baseline median 60.85, day 4 64.60, P = 0.162).