Analysis of cytokine gene expression during fetal thymic ontogeny using the polymerase chain reaction
Montgomery, R.A.; Dallman, M.J.
Journal of Immunology 147(2): 554-560
1991
ISSN/ISBN: 0022-1767 PMID: 1649220 Document Number: 377712
The expression of 12 cytokine and cytokine receptor gene during mouse thymic ontogeny has been studied using the polymerase chain reaction. The data reveal that IL-2 gene transcription does not begin in the thymus until fetal day (Fd) 16. However, IL-2R .beta.-chain mRNA was detectable throughout the period of investigation, from Fd 14 to 20. This suggests that the potential for high or intermediate affinity IL-2 binding is present in the thymus before the IL-2 gene is actually expressed. Overall, cytokine gene induction occurred in two distinct patterns. In the first group, represented by IL-1.beta., IL-4, IL-5, IL-6, IL-7 FN-.gamma., and lymphotoxin (lymphotoxin or TNF-.beta.) there was detected mRNA present from Fd 14 t 20. IL-1.alpha., IL-2, IL-3, and GM-CSF followed a second pattern in which gene induction was delayed until Fd 16. The expression of IL-7 and IL-2 genes showed an interesting temporal relationship. IL-7 mRNA transcription occurred before IL-2 but diminished from Fd 16 after the onset of IL-2 gene induction. Because these data reflect the in vivo progression of gene expression during T cell ontogeny, they provide a guideline for assessing the physiologic significance of thymocyte responses to cytokines at different stages of fetal development.