Acta Medica Okayama 29巻 2号

As a step in the elucidation of the mutual relationship between the degree of cancer progress and the antitumor activity of lymphocytes from different sites in cancer-bearing body, we isografted methylcholanthrene-induced tumor (MC-tumor) subcutaneously on the back of mice. The regional axillary lymph nodes, spleen and distant mesenteric lymph nodes were removed from these animals one, two, three, and four weeks later. We mixed lymphocytes prepared from these lymphatic tissues with primary MC-tumor culture cells and cultured together to estimate antitumor acitivity of lymphocytes from different sites. It has been found that a strong antitumor activity can be seen only in those regional axillary lymph node cells taken out one or two weeks after tumor transplatation and such an activity is weakened by three or four weeks. On the other hand, distant mesenteric lymph node cells one or two weeks after the transplantation have no antitumor activity as yet, while at the terminal cancer stage of four weeks there appears a stronger antitumor activity than that of regional lymph nodes. In the spleen, a strong antitumor activity can be observed in the third week after tumor transplantation, but the activity disappears by the fourth week. These findings support our previous findings in that for the tumor onset after the transplantation the antitumor activity seems to appear first in the regional lymph nodes, and when the tumor grows beyond a certain size, such an activity diminishes while it appears in further distant lymphatic tissues.