title: Immune activation during infancy in healthy humans.
abstract: Immune activity during infancy was investigated using blood samples from 30 neonates and 52 healthy infants between 2 and 15 months of age attending for immunization. The purpose of this study was to assess the total immune activity of T cells using soluble interleukin-2 receptor (IL-2R) and interferon-gamma concentrations. These were compared with the proportion of CD4 CD45RO-, IL-2R (CD25)-, and transferrin receptor (CD71)-positive peripheral blood lymphocytes. The median duration of breast-feeding and of introduction of solid feeds was 4.2 and 4.0 months, respectively. Compared to neonates, the mean +/- SE soluble IL-2R concentration peaked at 4 months of age (1670 +/- 94 vs 3060 +/- 252 U/ml; P < 0.0001), as did pooled interferon-gamma levels. The percentage of CD4 CD45RO T cells remained low and the proportion of activated peripheral blood lymphocytes decreased during infancy. We conclude that noncirculatory immune activity is increased during infancy and this is associated with weaning.
authors.affiliation: Gastroenterology Unit, Queen Elizabeth Hospital, Woodville South, Australia.
authors.forename: A G
authors.initials: AG
authors.lastname: Cummins
authors.forename: B A
authors.initials: BA
authors.lastname: Eglinton
authors.forename: A
authors.initials: A
authors.lastname: Gonzalez
authors.forename: D M
authors.initials: DM
authors.lastname: Roberton
mesh_terms: D015703:Antigens, CD / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007107:Immune System / Q000502:physiology*; D016130:Immunophenotyping; D007223:Infant; D007371:Interferon-gamma / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology
chemical_list: D015703:Antigens, CD; D015375:Receptors, Interleukin-2; D007371:Interferon-gamma