NEUTROPHIL CHEMOATTRACTANTS GENERATED IN 2 PHASES DURING REPERFUSION OF ISCHEMIC MYOCARDIUM IN THE RABBIT - EVIDENCE FOR A ROLE FOR C5A ANDINTERLEUKIN-8
Cl. Ivey et al., NEUTROPHIL CHEMOATTRACTANTS GENERATED IN 2 PHASES DURING REPERFUSION OF ISCHEMIC MYOCARDIUM IN THE RABBIT - EVIDENCE FOR A ROLE FOR C5A ANDINTERLEUKIN-8, The Journal of clinical investigation, 95(6), 1995, pp. 2720-2728
The neutrophil chemoattractants generated in a model of myocardial inf
arction in the anesthetized rabbit were investigated. Coronary artery
occlusion was followed by reperfusion for periods from 5 min to 4.5 h.
Extracts of myocardial tissue in normal and post-ischemic zones were
tested for C5a and interleukin-8 (IL-8) using specific radioimmunoassa
ys. In the post-ischemic zone, immunoreactive C5a was detected within
5 min and rose progressively to reach a plateau at 3-4.5 h. In contras
t, immunoreactive IL-8 concentrations rose after a delay and were high
est at the last time point tested, 4.5 h. Myeloperoxidase activity lev
els, an index of neutrophil accumulation, rose progressively as the co
ncentrations of chemoattractants increased. Using cation exchange and
reversed phase HPLC, immunoreactive C5a and IL-8 co-eluted with authen
tic standards. Fractions taken at the C5a and IL-8 peaks from reversed
phase HPLC exhibited neutrophil aggregating activity which was neutra
lized by the respective antibody used in the radioimmunoassays. Deplet
ion of circulating neutrophils virtually abolished immunoreactive IL-8
in the post-ischemic myocardial tissue. These observations suggest a
sequential release of chemoattractants: the first, C5a is generated in
interstitial fluid, followed by IL-8 generated by infiltrating neutro
phils. Thus, over the time period studied, IL-8 generation would be ex
pected to be indirectly dependent on C5a production.