Cytokine gene expression in murine fetal intestine: potential for extrathymic T cell development.
An increasing body of evidence suggests that certain T cell subsets mature extrathymically in the epithelium of the intestine. In the studies reported here, the authors have analysed cytokine/growth factor gene expression, recombinase-activating gene RAG-1 and RAG-2 gene expression and terminal deoxynucleotidyl transferase (TdT) gene expression in mouse fetal intestine and fetal thymus and liver, two known haematopoietic tissues. Stem cell factor (SCF) and interleukin 7 (IL-7) message was abundant in all three tissues during fetal development. IL-2 and IL-4 were not expressed in fetal gut but IL-4 was weakly detected in fetal liver and thymus. IL-9 and IL-13 mRNA was detected in all fetal tissues and IL-15 mRNA was abundant in fetal intestine but only weakly expressed in fetal liver and thymus. mRNA for SCF, IL-7, IL-13 and IL-15 was also detected in fibroblast-like cell lines derived from fetal intestine. RAG-1 and RAG-2 mRNA was detected in all three fetal tissues. TdT mRNA was not detected in fetal gut or liver but was weakly expressed in (fetal day) fd19-20 fetal thymus. Long-term (> 6 weeks) in vitro growth of IEL was achieved by coculturing intraepithelial lymphocytes (IEL) with IL-7-secreting fibroblasts in the presence of SCF and IL-2. The data show that the fetal mouse gut provides a suitable environment for lymphocyte development and receptor rearrangement, similar to fetal thymus and liver, even though expansion of intestinal IEL is delayed until 2-3 weeks after birth.
Murray
A M
AM
Discipline of Pathology, University of Newcastle, NSW, Australia.
Simm
B
B
Beagley
K W
KW
D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics*; D004253:DNA Nucleotidylexotransferase / Q000096:biosynthesis / Q000235:genetics; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004847:Epithelial Cells; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D019426:Integrases; D007376:Interleukin-2 / Q000235:genetics / Q000378:metabolism; D015851:Interleukin-7 / Q000235:genetics / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology / Q000196:embryology; D008099:Liver / Q000196:embryology / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger; D045522:Recombinases; D019089:Stem Cell Factor / Q000096:biosynthesis / Q000235:genetics; D013601:T-Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000196:embryology / Q000378:metabolism
D016207:Cytokines; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D007376:Interleukin-2; D015851:Interleukin-7; D012333:RNA, Messenger; C499308:Rag2 protein, mouse; D045522:Recombinases; D019089:Stem Cell Factor; C064655:V(D)J recombination activating protein 2; C064658:RAG-1 protein; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C115006:integron integrase IntI1; D004253:DNA Nucleotidylexotransferase