Distinct growth factor activity of interleukin 4 to the proliferation of the subsets of cd4 positive cd8 negative and cd4 negative cd8 positive thymocytes in mice
Chen W F.
Zhonghua Weishengwuxue He Mianyixue Zazhi 9(4): 227-232
A filler cell-free single T cell culture system and limit-dilution assay have been adopted for the analysis of the proliferative T lymphocyte precursor (PTL-p) frequency in the subpopulations of thymocytes in response to interleukin 4 (IL-4). Under the stimulation of phorbol myristate acetate (PMA) plus ionomycin, the PTL -p frequency of cortisone-resistant thymocytes (CRT), CD4+CD8- thymocytes and CD4-CD8+ thymocytes was 54.0 .+-. 15.3%, 12.1 .+-. 1.9% and 49.1 .+-. 6.7% respectively in response to IL-4, and resulted in the respective clone size of 19.8 .+-. 22.4, 4.1 .+-. 1.4 and 37.7 .+-. 53.9 cells per clone scored on day 4 of culture, obtained in single cell culture system. These results were conformed by limit-dilution assay, the IL-4 responsive-PTL -p frequency in CD4+ CD8- CRT was 0.092 .+-. 0.007, whilst in CD4-CD8+CRT was 0.433 .+-. 0.034. For the comparison, the number of IL-2 responsive precursors in thymocyte subpopulations were estimated. Under the culture condition of PMA + ionomycin + IL-2, the PTL-p frequency of CRT, CD4+ CD8- thymocytes and CD4-CD8+ thymocytes was 61.5 .+-. 6.8%, 39.6 .+-. 8.8% and 58.9 .+-. 3.0% respectively. Thus, the potency of IL-4 as a growth factor for T cells varies, dependent on the subsets of T cells it acts on. IL-4 is a potent growth factor for CD4-CD8+ thymocytes, though less effective than IL-2. By contrast, IL-4 is a very weak growth factor for CD4+CD8- thymocytes. In bulk culture, however, IL-4 was as potent as IL-2 for the supporting of CRT proliferation. It implies that IL-4 might induce the production of other factors which are required for the continuous cell proliferation in the later phase of growth.