HYPERCHOLESTEROLEMIA INCREASES MANGANESE SUPEROXIDE-DISMUTASE IMMUNOREACTIVE MACROPHAGES IN MYOCARDIUM

The effect of hypercholesterolemia on manganese superoxide dismutase ( MnSOD)-containing macrophages was investigated in male New Zealand whi te rabbits. Macrophages from control animals, which were marked with t he RAM-11 antibody, demonstrated co-localization with MnSOD immunoreac tivity, e.g. in the peri- and paravascular space within the myocardium , but not in the bone marrow. In rabbits fed a 0.5% cholesterol-enrich ed diet for 42 days, a significant increase (P<0.01) of MnSOD-immunore active macrophages within the myocardium was found concomitant to the drastic elevation of serum cholesterol level. In the bone marrow, MnSO D immunoreactivity did not change after cholesterol feeding. Thus in c holesterol-fed rabbits, the increase of MnSOD-containing macrophages s eems to parallel that of lipoproteins. MnSOD is considered as being pr otective against the cytotoxic effects of those superoxide anions, pos sibly generated in macrophages, which are involved in the metabolism o f modified lipoproteins.