Identification and Characterization of Soluble Factors That Induce Lymphocyte Infiltration into Tumor Undergoing Rejection

Fischer rats gained immunity against syngeneic gliosarcoma cells (T9) after repeated immunization with T9 cells. It was found that there was prominent infiltration of killer T cells into the tumor tissues of immune rats. However the mechanisms that regulates the degree of lymphocyte infiltration into tumor tissues is not clear. Inoculation of tumor cells into the foot pads of normal or immune rats resulted in a swelling of the regional lymph nodes. The swelling of regional lymph node subsides after 4 days in immune rats, but not in normal rats. It was noted that the reduction of lymph node swelling coincided with the massive infiltration of lymphocytes into tumor tissues. These data collectively suggested the possible existence of soluble factors at tumor sites which might regulate the degree of lymphocyte infiltration. The microfilter method using modified Boyden chambers was employed to evaluate lymphocyte migration activity. It was demonstrated that lymphocytes showed a strong migration toward culture supernatants of tumor tissue when tumor tissues were obtained within 12 hours after tumor inoculation. The lymphocyte migration activity was found specifically in the culture supernatant obtained from tumor tissues of T9-inoculated T9-sensitized rats. Cells were separated from tumor tissues of immune rats at 12 hours after inoculation of the tumor. Cell fractionation study indicated that neutrophils were responsible for the production of lymphocyte migration factor(s) (LMF). Fast protein liquid chromatography (FPLC) revealed that LMF are composed of multiple components with molecular weights of more than 67,000, 43,000, 27,000 and 17,000 with difirent isoelectric ?points and negative charges. The factors showed different migration activities toward T and B lymphocytes