I. Daniels et al., ROLE OF ARACHIDONIC-ACID AND ITS METABOLITES IN THE PRIMING OF NADPH OXIDASE IN HUMAN POLYMORPHONUCLEAR LEUKOCYTES BY PERITONEAL-DIALYSIS EFFLUENT, Clinical and diagnostic laboratory immunology, 5(5), 1998, pp. 683-689
Peritoneal dialysis effluent (PDE) contains a low-molecular-weight sol
ute that will activate and prime the NADPH oxidase of human neutrophil
s via a phospholipase A(2) (PLA(2))-dependent mechanism. Since the pro
ducts of PLA(2) are known to activate and prime the oxidase we have in
vestigated their role in the dialysis effluent-mediated activation and
priming of human neutrophils. NADPH oxidase activity of PDE-primed an
d -unprimed neutrophils was measured by lucigenin-enhanced chemilumine
scence in the presence of known inhibitors of the arachidonic acid cas
cade. Incubation of neutrophils with the nonselective PLA(2) inhibitor
quinacrine (0 to 100 mu M) reduced oxidase activity in both primed an
d unprimed cells. Furthermore, primed cells were more sensitive to the
action of quinacrine than were unprimed cells, We were unable to dete
rmine the relative roles of secretory PLA(2) (sPLA(2)) and cytosolic P
LA(2) (cPLA(2)) since the selective sPLA(2) inhibitor scalaradial (0 t
o 100 mu M) inhibited oxidase activity in both groups of cells by simi
lar degrees, while the specific cPLA(2) inhibitor AACO-CF3 (0 to 50 mu
M) failed to affect activity in either group. Inhibition of platelet-
activating factor (PAF), cycloxygenase, and 5-lipoxygenase-activating
protein by hexanolamino-PAF (0 to 25 mu M), flurbiprofen (0 to 25 mu M
), and MK886 (0 to 5 mu M), respectively, had no effect upon oxidase a
ctivity. However, the direct inhibition of 5-lipoxygenase by caffeic a
cid or lipoxin A(4) resulted in a similar concentration-dependent atte
nuation of oxidase activity in both primed and unprimed cells. Leukotr
iene B-4 (LTB4) release from primed neutrophils was comparable to that
from unprimed cells with the exception of phorbol myristate acetate-s
timulated cells, which released fivefold more LTB4 than control. Taken
together, these results suggest that it is arachidonic acid per se, a
nd not its metabolites, that is important in priming of the neutrophil
NADPH oxidase by dialysis effluent.