Dietary fat affects lipids and anti-cardiolipin antibody levels in autoimmune-prone NZB/W F1 mice

Studies in autoimmune-prone NZB/W F1 mice have demonstrated that the amount of dietary fat can affect autoantibody production and the disease course of autoimmune diseases. Anti-cardiolipin antibodies have been found to play a major role in thrombus formation and the increase of abortion rate in both human lupus patients and murine lupus. The present study investigated further the effect of dietary fat on lipid and anti-cardiolipin antibody production in autoimmune-prone mice. Two groups of NZB/W F1 mice were fed on diets containing 200 g dietary fat/kg and 50 g dietary fat/kg respectively, the fat being composed of equal amounts of lard and soyabean oil. Serum levels of lipids, immunoglobulin (Ig) anti-single stranded DNA and anti-cardiolipin antibodies were followed regularly every month and mice were killed for in vitro experiments after 5 months on the experimental diets. The results showed that serum triacylglycerol concentration was lower in mice fed on the high-fat diet than in those fed on 50 g fat/kg. There was no significant difference in hepatic lipid contents; however, the fatty acid contents were different between these two groups. Hepatic linoleic acid (18:2n-6) and arachidonic acid (20:4n-6) concentrations were higher in mice fed on the high-fat diet. There were no significant differences in serum IgM concentrations or IgM anti-cardiolipin antibody levels between these two groups. However, IgG anti-cardiolipin antibody levels were higher in mice fed on the high-fat diet at the age of 3-4 months. Total serum IgG concentration was noted to be higher, but in contrast, serum IgA was lower, in the high-dietary-fat group. These findings suggest that high dietary fat may affect lipid metabolism and autoantibody levels in autoimmune diseases.