Presence of CD8 alpha-CD8 beta-positive TcR gamma/delta thymocytes in the fetal murine thymus and their in vitro expansion with interleukin-7 (original) (raw)
Related papers
Experimental Hematology, 1999
The possibility that mature lymphocytes play a role in the regulation of human T cell development was studied in the experimental model of fetal thymus organ cultures (FTOC), by reconstituting lymphocyte-depleted murine fetal thymus (FT) lobe with cells isolated from human umbilical cord blood (CB). Cultures were incubated with human cytokines (IL-7, FLT-3 ligand and Steel Factor), or remained untreated. When CD4 ϩ , or CD8 ϩ CB cells, were co-cultured with FT explants, they expanded and maintained their original phenotypic markers, with no significant effect of the cytokines. Cultures of human hematopoietic stem cells (CD34 ϩ ) gave rise to CD4 ϩ CD8 Ϫ cells, which were mainly CD3 Ϫ , with no indication of further intermediate developmental stages. However, a limited number of CD4 ϩ CD8 ϩ (double positive [DP]) cells were detected when the CD34 ϩ cells were co-cultured with CD4 ϩ cells from the same CB samples. In contrast, FT with unseparated CB cells resulted in the different CD4/CD8 subsets, and their numbers increased in the presence of cytokines. The appearance of DP cells depended on the presence of either CD4 ϩ or CD8 ϩ cells in the cultured CB samples. Hence, DP cells were not detected when the CB was depleted of CD4 ϩ and CD8 ϩ cells ("depCB") before culture, and they appeared when depCB were co-cultured with either CD4 ϩ or CD8 ϩ cells. In contrast, CD4 ϩ cells inhibited the development of CD8 ϩ CD3 ϩ cells, and this was most pronounced in the absence of the cytokines. There was no symmetrical down-regulatory effect of CD8 ϩ cells on the development of CD4 ϩ CD3 ϩ cells. Addition of IL-15 to the cytokine mixture led to an increased proportion of CD56 ϩ cells in cultures of CD34 ϩ cells. The presence of CD4 ϩ , and not CD8 ϩ cells, interfered with this process. Our results thus imply differential effects of CD4 ϩ and CD8 ϩ cells on thymocytopoiesis.
Immunology, 1997
In this report we have studied the influence of interleukin-7 (IL-7) on thymocyte differentiation by evaluating the effects of IL-7 on the generation of T-cell receptor-ap (TCR-ac4) and TCR-'y6 thymocyte subpopulations in rat fetal thymus organ culture. IL-7 enhanced the differentiation pathway of TCRac4 thymocytes, first increasing the numbers of immature CD8+ cells, and later those of both CD4+CD8+ and mature thymocytes. The kinetics of thymocyte migration out of thymic lobes was also accelerated, and the average number of mature TCRC43hi emigrants per day was increased in the presence of IL-7. Moreover, mature CD4-CD8+ thymocytes were preferentially generated after IL-7 administration. This TCR-c4h1 cell population was not actively dividing, indicating that IL-7-promoted thymocyte differentiation was selective to the CD8 cell lineage. Distribution of some TCR-Vac and TCR-V,3 segments among mature thymocytes was also modified in IL-7-treated thymic lobes. On the contrary, the maturation of TCR-y6 was not affected by IL-7 addition during the first days of culture, but their numbers sharply increased by day 6 of culture. These results were confirmed with IL-7-treated cultures for 24 hr, showing that IL-7 responsiveness was acquired by TCR-'y6 cells late in thymus ontogeny. The present results thus indicate a key role for IL-7 in the maturation of TCR-acp thymocytes and the expansion of thymic TCR-'y8 cells.
Responsiveness of fetal and adult CD4-, CD8- thymocytes to T cell activation
The Journal of Immunology
Day-14 fetal CD4-, CD8- thymocytes showed a greater proliferative response to PMA + IL-4 than did adult double-negative thymocytes. In contrast, adult double-negative thymocytes were more responsive to PMA + IL-1 + IL-2 or to IL-1 + IL-2 alone. The adult double-negative thymocytes showed significantly greater proliferation than fetal thymocytes after stimulation via anti-CD3 or anti-Thy-1 in the presence or absence of interleukins (IL-1 + IL-2 or IL-4). Adult CD4-, CD8- thymocytes also exhibited greater calcium mobilization following anti-CD3 stimulation IL-2-dependent activation with anti-Thy-1 or IL-1 + IL-2 in the absence of PMA resulted in marked expansion of CD 3+, F23.1+, CD4-, CD8- thymocytes, a population absent in fetal thymocytes but constituting 4% of pre-cultured CD4-, CD8- adult thymocytes. IL-4 + PMA failed to expand this CD 3+ population. It is hypothesized that before expression of functional TCR, T cell development may be more dependent on activation pathways not us...
Cellular Immunology, 1992
Using fetal thymic organ culture (FTOC), we describe the effects of IL-I on T cell differentiation, particularly within the CD4-CD8-subset. While treatment of FTOC with ILl led to a modest reduction in total thymocyte yield, it induced an increase in the percentage of CD4-CD8-cells that express IL-2R early in culture and a decrease in the number of their precursors (CD44+IL-2R-cells). The increase in the percentage of cells expressing IL-2R was not accompanied by an increase in the number of these cells. At later time points these IL-2R+ cells (and their precursors) were reduced relative to controls. The total number of CD4-CD8-CD3-precursor cells in IL-ltreated cultures was reduced to approximately half that in controls at Day I2 of culture. However. only minor inhibition of total cell number was observed, which, taken together with the greater frequency of IL-2R+ precursors, suggests that this depletion of the pool of precursors may have been due to the induction ofpremature differentiation rather than to its inhibition. B 1992Academic Press. Inc.
Cell Immunol, 1992
This study examined the involvement of c-for protooncogene in thymocyte development from lymphohemopoietic T cell progenitors, within the thymic microenvironment. We first analyzed the thymocytes developing in vitro in the fetal thymus from the c-j& transgenic mice and found a high proportion of CD4+ single positive (SP) cells. We then seeded either fetal liver or hone marrow (BM) cells from normal donors onto lymphocyte-depleted fetal thymus explants of c-fos transgenic mice. The results showed an increased proportion of mature CD4+ SP and decreased CD4+CD8+ double positive (DP) cells. A similar pattern of CD4/CD8 thymocyte subsets was observed when either thymus or BM cells from c-j& transgenic mice developed within a normal thymic stroma. The kinetics of thymocyte development in organ culture (from Days 3 to 11) suggested that the SP cells obtained under these conditions may have bypassed the CD4+CD8+ DP phase. It appears that the altered pattern of thymocyte development manifested in adult cfis transgenic mice can be induced by the early embryonic thymic stroma, and may also involve cells in the lymphohemopoietic tissues. 0 1992 Academic PKSS, IX.