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Changes in lymphocyte subsets following multiple administration of recombinant interleukin-2 plus recombinant
M Iigo1, K Nishikata, Y Nakajima
1Chemotherapy Division, National Cancer Center Research Institute, Tokyo.
Treatment with a combination of recombinant human interleukin-2 (rHIL-2) and recombinant mouse interferon-beta (rIFN-beta) or -gamma (rIFN-gamma) showed a significant antitumor effect against sc adenocarcinoma 755 in mice, although treatment with either one alone had almost no effect. The combination of rHIL-2 and rIFN-beta caused regression of the tumor but the combination of rHIL-2 and rIFN-gamma did not. Injection of tumor-bearing mice with the combinations of rHIL-2 and rIFN resulted in marked increases in the total number of peritoneal lymphocytes, and the frequency of Lyt-2+ cells was more markedly increased by the combination of rHIL-2 and rIFN-beta than by the combination of rHIL-2 and rIFN-gamma. In Winn assay, elimination of the Lyt-2+ population abolished the protective capacity of the peritoneal cells. The subsets of thymocytes were drastically changed when mice were bearing a tumor or were treated with cytokines. In particular, Lyt-2+/L3T4+ cells were decreased in tumor-bearing mice, but many Lyt-2+/L3T4+ cells were maintained in the thymus by treatment with a cytokine alone. When treated with rHIL-2 and rIFN-beta, the Lyt-2+/L3T4+ cells were markedly decreased, while Lyt-2+/L3T4- T-cells were increased, but these subsets were little changed by treatment with rHIL-2 plus rIFN-gamma. Thus, injections of rHIL-2 and rIFN-beta into tumor-bearing mice resulted in a high frequency of Lyt-2+/L3T4- cells in the peritoneal cavity, together with changes in the T-cell subsets in the thymus. These results suggest that maturation of T-cells in the thymus may be an important step in the pathway by which cytokine treatment brings about regression of tumors.
Treatment with a combination of recombinant human interleukin-2 (rHIL-2) and recombinant mouse interferon-beta (rIFN-beta) or -gamma (rIFN-gamma) showed a significant antitumor effect against sc adenocarcinoma 755 in mice, although treatment with either one alone had almost no effect. The combination of rHIL-2 and rIFN-beta caused regression of the tumor but the combination of rHIL-2 and rIFN-gamma did not. Injection of tumor-bearing mice with the combinations of rHIL-2 and rIFN resulted in marked increases in the total number of peritoneal lymphocytes, and the frequency of Lyt-2+ cells was more markedly increased by the combination of rHIL-2 and rIFN-beta than by the combination of rHIL-2 and rIFN-gamma. In Winn assay, elimination of the Lyt-2+ population abolished the protective capacity of the peritoneal cells. The subsets of thymocytes were drastically changed when mice were bearing a tumor or were treated with cytokines. In particular, Lyt-2+/L3T4+ cells were decreased in tumor-bearing mice, but many Lyt-2+/L3T4+ cells were maintained in the thymus by treatment with a cytokine alone. When treated with rHIL-2 and rIFN-beta, the Lyt-2+/L3T4+ cells were markedly decreased, while Lyt-2+/L3T4- T-cells were increased, but these subsets were little changed by treatment with rHIL-2 plus rIFN-gamma. Thus, injections of rHIL-2 and rIFN-beta into tumor-bearing mice resulted in a high frequency of Lyt-2+/L3T4- cells in the peritoneal cavity, together with changes in the T-cell subsets in the thymus. These results suggest that maturation of T-cells in the thymus may be an important step in the pathway by which cytokine treatment brings about regression of tumors.