['To investigate the distribution of regulatory T-lymphocytes in the splenocytes cocultured with syngeneic low-immunogenic tumor cells, as compared with that of highly-immunogenic tumor cells, to investigate the mechanism underlining tumor evasion.', 'Three different immunogenic tumor cells were cocultured with syngeneic splenocytes individually to mimic cancer immunity in vitro. The proliferation response of splenocytes was measured by thymidine incorporation. The distribution of TR cells, CD4(+) IFN-gamma (+) T cells and CD4(+) IL-10(+) T cells were analyzed by flow cytometry. The secretion of IFN-gamma and IL-10 in supernatants was measured by ELISA assay.', 'The stimulation Index of splenocytes cocultured with syngeneic highly-immunogenic H22 or FBL3 was much higher than that of poorly immunogenic melanoma D5. In each group, stimulation Index of splenocytes cocultured with allogeneic tumor cells was higher than that of the corresponding tumor immunity model. In addition, compared with those of highly-immunogenic tumors, there were more TR, CD4(+)IL-10(+) and less CD4 (+)IFN-gamma(+) T cells in the splenocytes, and higher IL-10 and lower IFN-gamma levels in the supernatant of the splenocytes stimulated with low-immunogenic D5 cells.'] Is [ Poorly-immunogenic tumor capable of inducing proliferation of CD4 ( + ) CD25 ( + ) regulatory T-lymphocytes in vitro ]?