Effect of long-term feeding of corn oil or coconut oil diets on immune response and prostaglandin E 2 synthesis of squirrel and cebus monkeys

Abstract

The in vitro and in vivo immune response was investigated in adult squirrel and cebus monkeys fed corn oil (CORN) or coconut oil (COCO) diets (31% calories as fat) since birth. The in vitro blastogenic response of lymphocytes cultured in calf serum or in autologous serum to T- and B-cell mitogens was compared between the two species fed the two types of fat. For in vivo measurements of immune competence, all monkeys received measles vaccine and their serum antibody titers were measured by hemagglutination inhibition assay along with measurement of IgG, IgM and IgA. Prostaglandin E 2 synthesis by peripheral blood mononuclear cells (PBMC) was measured following stimulation with calcium ionophore. Cells cultured in either calf or autologous serum responded in the same relative fashion to mitogens. However, culturing cells in autologous serum exaggerated the dietary differences found. Cebus monkey lymphocytes were more responsive than squirrel monkeys, but squirrel monkeys fed corn oil had the lowest blastogenic responses to T-cell and B-cell mitogens and lower antibody titers to measles vaccine. Cebus monkey PBMC also generated less PGE 2 than those from squirrel monkeys. The data suggest that genetic variation in phospholipid metabolism, possibly including PGE 2 synthesis, may underlie differences in the immune response to dietary fat unsaturation by these two species of monkeys.