Interleukin 8 (IL-8) is a potent chemotactic and activating agent for human
neutrophils and bovine IL-8 is chemotactic for bovine neutrophils; however
, it is unclear whether IL-8 activates bovine neutrophils. Two isoforms of
human recombinant (hr) IL-8 protein (77 and 72 amino acid) were used to sti
mulate bovine neutrophils in vitro. Bovine neutrophils exhibited significan
t migration in the presence of 0.1, 0.5, 1.0 and 5.0 ng ml(-1) hr IL-8 when
incubated for 30 min at 37 degrees C in a modified Boyden chamber assay. B
oth the 77 and 72 aa forms were-equally effective in inducing migration in
this assay. At the highest doses of IL-8 examined (1 and 5 ng ml(-1)), migr
ation was similar to migration in the presence of 20% zymosan-activated ser
um (ZAS) or 12 h lipopolysaccharide (LPS)-stimulated blood monocyte superna
tants (CM). Significant (p<0.05) release of alkaline phosphatase (ALK-P) (f
rom specific granules) occurred but myeloperoxidase (MPO) release and super
oxide anion production were not enhanced in bovine neutrophils by either fo
rm of hrIL-8 at any of the doses tested. Significant (p<0.05) alkaline phos
phatase release was observed in the presence of 10 and 100 ng ml(-1) for th
e 72 aa form of IL-8 and only at the higher dose for the 77 aa form of IL-8
. The ZAS and CM significantly enhanced neutrophil degranulation of ALK-P a
nd MPO as well as inducing superoxide anion production. These results sugge
st that IL-8 may play a role in both neutrophil recruitment and activation
during bovine inflammatory processes. (C) 2000 Elsevier Science B.V. All ri
ghts reserved.