Chervenak R, Dempsey D, Soloff R S, Smithson G
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130.
J Immunol. 1992 Nov 1;149(9):2851-6.
The growth requirements of bone marrow-resident cells that are able to differentiate along the T cell lineage (pre-T cells) have not been well established. We recently have shown that the T cell-derived lymphokine IL-3 is able to maintain pre-T cells in vitro for at least 2 weeks. However, in our initial studies, we were not able to ascertain whether IL-3 induced pre-T cell growth during culture, or whether IL-3 simply maintained the viability of these progenitors. To address this issue, we used a multiple dose assay system to assess the level of pre-T cell activity (thymic repopulation) in a selected population of bone marrow cells (CD3-, Thy-1.2+) both before and after culture in IL-3. In addition, we tested the potential role of mast cell growth factor (MGF) in the growth and maintenance of pre-T cells in vitro. The results of these studies showed that IL-3 produced a modest, but consistent increase in the pre-T cell activity during culture. Culture of CD3-, Thy-1.2+ bone marrow cells in MGF also resulted in an increase in the total amount of detectable pre-T cell activity among the cultured cells. The most dramatic increases in pre-T cell activity, however, were induced by the culture of the selected marrow cells in both MGF and IL-3. Cultures supplemented with both cytokines produced net increases in pre-T cell activity of 40- to 75-fold after 10 days of culture. Because the increases in pre-T cell activity were not accompanied by observable increases in the size of thymic colonies produced by the pre-T cells, the increased levels of pre-T cell activity appeared to result from increases in pre-T cell numbers during culture. Thus, in addition to the other activities ascribed to MGF, this cytokine displays pre-T cell growth factor activity and can synergize with IL-3 in that capacity. The use of MGF in conjunction with IL-3 provides the best system described to date for the propagation of pre-T cells in primary bone marrow cell cultures.
能够沿T细胞谱系分化的骨髓驻留细胞（前T细胞）的生长需求尚未完全明确。我们最近发现，T细胞衍生的淋巴因子IL-3能够在体外维持前T细胞至少2周。然而，在我们最初的研究中，我们无法确定IL-3在培养过程中是否诱导了前T细胞的生长，或者IL-3是否只是维持了这些祖细胞的活力。为了解决这个问题，我们使用了多剂量检测系统来评估在IL-3中培养前后选定的骨髓细胞群体（CD3-，Thy-1.2+）中的前T细胞活性水平（胸腺再填充）。此外，我们测试了肥大细胞生长因子（MGF）在体外前T细胞生长和维持中的潜在作用。这些研究结果表明，IL-3在培养过程中使前T细胞活性有适度但持续的增加。在MGF中培养CD3-，Thy-1.2+骨髓细胞也导致培养细胞中可检测到的前T细胞活性总量增加。然而，前T细胞活性最显著的增加是由在MGF和IL-3中培养选定的骨髓细胞诱导的。补充了两种细胞因子的培养物在培养10天后使前T细胞活性净增加了40至75倍。由于前T细胞活性的增加并没有伴随着前T细胞产生的胸腺集落大小的明显增加，前T细胞活性水平的增加似乎是由于培养过程中前T细胞数量的增加。因此，除了归因于MGF的其他活性外，这种细胞因子还表现出前T细胞生长因子活性，并且可以在该能力方面与IL-3协同作用。将MGF与IL-3结合使用为迄今为止描述的在原代骨髓细胞培养物中扩增前T细胞提供了最佳系统。
