Polyunsaturated fatty acids and T-cell function: Implications for the neonate

Infant survival depends on the ability to respond effectively and appropriately to environmental challenges. Infants are born with a degree of immunological immaturity that renders them susceptible to infection and abnormal dietary responses (allergies). T-lymphocyte function is poorly developed at birth. The reduced ability of infants to respond to mitogens may be the result, of the low number of CD45RO+ (memory/antigen-primed). T cells in the infant or the limited ability to produce cytokines particularly interferon-γ, interleukin (IL)-4, and IL-10]. There have been many important changes in optimizing breast milk substitutes for infants; however, few have been directed at replacing factors in breast milk that convey immune benefits. Recent research has been directed at the neurological, retinal, and membrane benefits of adding 20∶4n−6 (arachidonic acid; AA) and 22∶6n−3 (docosahexaenoic acid; DHA) to infant formula. In addults and animals, feeding DHA affects T-cell function. However, the effect of these lipids on the development and function of the infant's immune system is not known. We recently reported the effect of adding DHA+AA to a standard infant formula on several functional indices of immune development. Compared with standard formula, feeding a formula containing DHA+AA increased the proporition of antigen mature (CD45RO+) CD4⁺ cells, improved IL-10 production, and reduced IL-2 production to levels not different from those of human milk-fed infants. This review will briefly describe T-cell development and the potential immune effect of feeding long-chain polyunsaturated fatty acids to the neonate.