Involvement of IL-7 in the development of gamma delta T cells in the thymus.
The effect of IL-7 on the growth of thymic T lymphocytes was investigated by adding recombinant IL-7 into cell suspension cultures and submersion organ cultures (SOC) of murine fetal thymuses (FT) and newborn thymuses (NBT). FT and NBT were obtained from C57BL/6 mice at day 15 of gestational age and at day 3 after birth, respectively. In both cell suspension cultures and SOC, addition of IL-7 highly improved the cell recovery. In cell suspension cultures, addition of IL-7 resulted in the growth of gamma delta T-cells from FT-cells, whereas the same cytokine promoted the growth of both alpha beta and gamma delta T-cells from NBT-cells. These results may indicate that this cytokine is able to support the proliferation of T-cells of both alpha beta and gamma delta lineages. In marked contrast, in SOC, addition of IL-7 resulted in the growth of gamma delta T-cells not only in FT but also in NBT, despite the fact that the SOC of NBT without exogenous cytokine exclusively promoted the growth of alpha beta T-cells. A similar effect was also seen when IL-2 was added to NBT-SOC, though the skewing to gamma delta lineage was not so strong as in the case of IL-7. In addition, we found that IL-7 mRNA is expressed in the day 15 FT at a much higher level than in the adult thymus. These results strongly suggested that the production of a large amount of IL-7 synthesized in the FT is one of the major factors leading to the generation of gamma delta T-cells in FT.
Tomana
M
M
Department of Zoology, Faculty of Science, Kyoto University, Japan.
Ideyama
S
S
Iwai
K
K
Gyotoku
J
J
Germeraad
W T
WT
Muramatsu
S
S
Katsura
Y
Y
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000235:genetics; D015851:Interleukin-7 / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology* / Q000196:embryology
D007376:Interleukin-2; D015851:Interleukin-7; D012333:RNA, Messenger; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta