Antiatherosclerotic effects of the Fc portion of immunoglobulin in apolipoprotein E-deficient mice

The mechanisms and importance of the Fc portion of immunoglobulin on experimental atherosclerosis in apolipoprotein E-deficient mice were examined. Experimental atherosclerosis was induced in mice fed a high fat diet containing 0.3% cholesterol. Over eight and 16 weeks, the mice were treated with intraperitoneal injections (1 g/kg/day) of either human intact immunoglobulin or F(ab′)₂ fragments of human immunoglobulin on alternate days. Fatty streak formation and fibro-fatty plaques were markedly suppressed in mice that received intact immunoglobulin for eight and 16 weeks. In contrast, atherosclerotic lesions did not improve in mice that received F(ab′)₂ fragments. Differences in lesion area did not correlate with any significant alterations in serum lipid levels. Immunoglobulin therapy markedly suppressed atherosclerosis due to Fc receptor-mediated anti-inflammatory and immunomodulating actions.