Role of IL-2 in rat fetal thymocyte development.
Early during rat thymus ontogeny, an important proportion of thymocytes expresses IL-2R and contains IL-2 mRNA. To investigate the role of the IL-2-IL-2R complex in rat T cell maturation, we supplied either recombinant rat IL-2 or blocking anti-CD25 mAb to rat fetal thymus organ cultures (FTOC) under several experimental conditions. The IL-2 treatment initially stimulated the growth of thymocytes and, as a result, induced T cell differentiation, but the continuous addition of IL-2 to rat FTOC, as well as the anti-CD25 administration, resulted in cell number decrease and inhibition of thymocyte maturation. These results indicate that immature rat thymocytes bear functional high-affinity IL-2R and that IL-2 promotes T cell differentiation as a consequence of its capacity to stimulate cell proliferation. Modifications in TCR alpha beta repertoire and increased numbers of NKR-P1+ cells, largely NK cells, were also observed in IL-2-treated FTOC. Furthermore, IL-2-responsiveness of different thymocyte subsets changed throughout thymic ontogeny. Immature CD4-CD8-cells responded to IL-2 in two stages, early in thymus development and around birth, in correlation with the maturation of two distinct waves of thymic cell progenitors. Mature CD8+ thymocytes maximally responded to IL-2 around birth, supporting a role for IL-2 in the increased proliferation of mature thymocytes observed in vivo in the perinatal period. Taken together, these findings support a role for IL-2 in rat T cell development.
Varas
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Department of Cell Biology, Faculty of Biology, Complutense University, Madrid, Spain.
Vicente
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Romo
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T
Zapata
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AG
D000818:Animals; D000831:Animals, Newborn; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001483:Base Sequence; D002454:Cell Differentiation; D002455:Cell Division; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005333:Fetus / Q000166:cytology / Q000276:immunology; D007376:Interleukin-2 / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology; D009924:Organ Culture Techniques; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015375:Receptors, Interleukin-2 / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology
D000911:Antibodies, Monoclonal; D017931:DNA Primers; D007376:Interleukin-2; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins