AIM: To examine whether oxidized low density lipoproteins (ox-LDL) mig
ht induce apoptosis in mouse peritoneal macrophages (MPM). METHODS: Lo
w density lipoproteins (LDL) were isolated from healthy human plasma b
y ultracentrifugation and oxidized by CuSO4 10 mu mol . L(-1). MPM wer
e incubated in a medium containing ox-LDL, LDL, or phosphate-buffer so
lution (PBS) as control. DNA fragmentation was visualized by agarose g
el electrophoresis and determined quantitatively using Hoechst 33258 f
luorochrome. RESULTS: Ox-LDL, not LDL, elicited typical apoptotic morp
hological changes (shrinkage of cytoplasm and condensation of chromati
n) and DNA fragmentation in a time- and dose-dependent manner. Incubat
ion for 24 h was necessary for ox-LDL 200 mg protein . L(-1) to induce
DNA fragmentation, and the maximal effect reached at 72 h. The DNA fr
agmentation after 24-h incubation with ox-LDL at concentrations of 100
, 200, and 400 mg protein . L(-1) amounted to 0.0 % (P > 0.05), 9.3 %
(P < 0.05), and 30.9 % (P < 0.01), respectively vs PBS control. Dextra
n sulfate, a scavenger receptor blocker and cycloheximide, a protein s
ynthesis inhibitor, exhibited no effect on DNA fragmentation. However,
antioxidant butylated hydroxytoluene (BHT) 20 mu mol . L(-1) complete
ly inhibited Cu2+-mediated oxidation of LDL as well as the apoptosis-i
nducing effect of Cu2+-exposed LDL. Lysophosphatidylcholine ( LPC), an
active component in ox-LDL, at concentration up to 60 mu mol . L(-1),
did not elicit DNA fragmentation in MPM. CONCLUSION: Ox-LDL induces a
poptosis in MPM without involving LPC.