A longitudinal study of gamma-interferon production by peripheral blood mononuclear cells from breast- and bottle-fed infants.

Production of gamma-interferon (gamma-IFN) in vitro by peripheral blood mononuclear cells (PBMC) from 15 breast-fed and 15 bottle-fed infants has been studied from birth to 9 months of age and compared with production by adult cells. Using a Terasaki plate microculture system with serum-free medium, PBMC were stimulated with staphylococcal enterotoxin A (SEA) and gamma-IFN production was assessed by an immunoradiometric assay. Cord blood mononuclear cells (CBMC) and PBMC from all infants secreted large quantities of gamma-IFN. The levels secreted did not change significantly with age over the 9 months of the study, nor did they differ from the levels secreted by adult cells. Cells from the bottle-fed infants secreted slightly more gamma-IFN than cells from breast-fed infants, but this difference was not significant. These results indicate that the potential for PBMC to secrete gamma-IFN in vitro is fully developed at birth in full-term infants and cannot therefore be further influenced by subsequent breast- or bottle-feeding. In addition, the greater susceptibility of infants than adults to certain bacterial and viral infections cannot be attributed to a deficiency in the potential of infant cells to secrete gamma-IFN in vitro.