title: Intestinal alpha beta T cells differentiate and rearrange antigen receptor genes in situ in the human infant.
abstract: Intestinal Ag exposure during neonatal life influences appropriate adult immune responses. To define the mechanisms shaping the T cell repertoire during this period, we examined T cell differentiation and receptor diversity in the intestine of human infants. Developmental phenotypes of intraepithelial and lamina propria intestinal T cells from infants aged 1 day to 2 years were assessed ex vivo by flow cytometry and in situ by triple-fluorescent immunohistochemistry. Gene recombination-specific enzymes were assessed by PCR. TCR beta-chain V region gene diversity was determined by sequencing. Several different early lineage T cell populations were present neonatally: CD3(+)4(-)8(-) T cells were present at birth and numbers decreased during the neonatal period; CD3(+)4(+)8(+) T cells were present in low numbers throughout infancy; and CD3(+)4(+)8(-) or CD3(+)4(-)8(+) T cells increased with age. Very early lineage T cells, CD3(-)2(-)7(+) and CD3(-)2(+)7(+), were present neonatally, but were essentially absent at 1 year. Most lamina propria T cells differentiated rapidly after birth, but maturation of intraepithelial T cells took place over 1 year. Intestinal samples from infants less than 6 mo old contained transcripts of T early alpha and TdT, and 15 of 19 infant samples contained mRNA for RAG-1, some coexpressing RAG-2. TCR beta-chain repertoires were polyclonal in infants. Immature T cells, pre-T cells, and genes involved in T cell recombination were found in the intestine during infancy. T cell differentiation occurs within the neonatal human intestine, and the TCR repertoire of these developing immature T cells is likely to be influenced by luminal Ags. Thus, mucosal T cell responsiveness to environmental Ag is shaped in situ during early life.
authors.affiliation: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA. Amanda.Williams@bristol.ac.uk
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Williams
authors.forename: Paul W
authors.initials: PW
authors.lastname: Bland
authors.forename: Anne C
authors.initials: AC
authors.lastname: Phillips
authors.forename: Susan
authors.initials: S
authors.lastname: Turner
authors.forename: Trevor
authors.initials: T
authors.lastname: Brooklyn
authors.forename: Gabriel
authors.initials: G
authors.lastname: Shaya
authors.forename: Richard D
authors.initials: RD
authors.lastname: Spicer
authors.forename: Christopher S J
authors.initials: CS
authors.lastname: Probert
mesh_terms: D000293:Adolescent; D000375:Aging / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002675:Child, Preschool; D002999:Clone Cells; D015332:Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D007231:Infant, Newborn; D007413:Intestinal Mucosa / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D007420:Intestine, Large / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D007421:Intestine, Small / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018655:Lymphocyte Count; D009928:Organ Specificity / Q000235:genetics / Q000276:immunology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis / Q000235:genetics*; D011995:Recombination, Genetic; D013234:Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta