Background-An important action of interleukin 8 (IL8) is stimulation o
f granulocytes. The object of this study was to assess the contributio
n of IL8 to the leucocyte-endothelial cell interactions associated wit
h intestinal inflammation in the rat. Methods Two indomethacin injecti
ons (48 and 24 hours prior to the experiments) induced a longlasting i
leitis in rats. The number of adherent and emigrated leucocytes, leuco
cyte rolling velocity, and shear rate were monitored in normal and inf
lamed mesenteric postcapillary venules. Some animals received a monocl
onal antibody (MAb) against IL8 or CD11b/CD18 at 24 and 12 hours prior
to the experiment. Results-Indomethacin elicited a sevenfold increase
in leucocyte adherence and a 5.4-fold increase in leucocyte emigratio
n, while leucocyte rolling velocity was reduced by nearly 80%. The ind
omethacin induced increases in leucocyte adherence and emigration were
significantly reduced (by 57% and 67%, respectively) while leucocyte
rolling velocity was increased (to 63% of control) by the IL8-specific
MAb. The level of inhibition seen with the IL8 MAb was similar to tha
t associated with administration of a MAb directed against the leucocy
te adhesion molecule CD11b/CD18. Conclusions-IL8 contributes to the le
ucocyte-endothelial cell interactions elicited in mesenteric venules b
y indomethacin.