Breast-fed and formula-fed infants do not differ in immunocompetent cell cytokine production despite differences in cell membrane fatty acid composition

Abstract

Breast-fed and formula-fed infants differ in the amount and type of polyunsaturated fatty acids consumed. The fatty acid composition of cell membranes is related to dietary fatty acids and, in adults, changes in membrane fatty acid composition are accompanied by changes in monocyte cytokine production and hence a modification of the immunologic response. Our objective was to determine whether production by immunocompetent cells of the proinflammatory cytokines interleukin 1 (IL-1) and tumor necrosis factor (TNF) differs between breast-fed and formula-fed infants. Twenty-six healthy infants (13 breast-fed and 13 fed modified cow-milk formula) aged 2-4 mo were studied. The fatty acid composition of red blood cell (RBC) membrane phospholipids was measured by gas-liquid chromatography and IL-1 and TNF release were measured in whole blood culture in bacterial-endotoxin-stimulated and unstimulated cells. The infants' ages, weights, hemoglobin concentrations, and white blood cell counts did not differ significantly between groups. The percentage of n-3 fatty acids of total RBC phospholipid fatty acids was significantly higher in breast-fed than in formula-fed infants (6.31 +/- 2.5% compared with 2.98 +/- 0.97%); docosahexaenoic acid (22:6n-3) concentrations were also markedly higher in breast-fed infants (5.1 +/- 1.2% compared with 2.2 +/- 0.9%, P: < 0.001), but eicosapentaenoic acid (20:5n-3) and docosapentaenoic acid (22:5n-3) concentrations did not differ significantly between groups. The percentage of n-6 fatty acids was not significantly different between groups. The percentage of oleic acid (18:1) was higher in formula-fed than in breast-fed infants (16.2 +/- 0.7% compared with 20.6 +/- 1.1%; P: < 0.001). IL-1 and TNF release in whole blood culture did not differ significantly between groups. The release of proinflammatory cytokines by immunocompetent cells does not differ significantly in breast-fed and formula-fed infants despite differences in cell membrane fatty acid composition.