Antitumour effect of interferon combined with hyperthermia against experimental brain tumour

A combined therapeutic modality with hyperthermia and locally administered rIFN-beta inhibited the growth of B16 melanoma in association with the modulation of cellular infiltrates

Murine B16-F10 melanoma was treated with local microwave hyperthermia, local injection of murine recombinant interferon-beta (rIFN-beta) or a combination of both in order to investigate the augmentation of anti-proliferative effects with this combination treatment. Concerning the local modulation of immunological reactions of the host, local hyperthermia at 43 degrees C for 15 min on murine melanoma caused remarkable infiltration of natural killer cells and local injection of rIFN-beta led to considerable infiltration of T cells. When these two modalities were combined, the infiltration of NK cells completely disappeared and, instead, remarkable augmentation of T cell infiltration occurred. Synergistic suppressive effects on melanoma growth with occasional scar formation were seen with this combined modality. These results indicate that local hyperthermia with a combination of rIFN-beta modulates local immune reactions of the host, and probably this immune reaction is partly involved in the course of the suppression of tumor growth.

Augmentation of in vitro cytolytic activity of LAK cells with heated ATL-derived cell lines

Three adult T-cell leukemia/lymphoma-derived cell lines, MT-2, MJ, and HUT102, were investigated to determine how they responded to hyperthermia, lymphokine-activated killer (LAK) cells, or a combination of both in vitro. All three cell lines showed a similar sensitivity to LAK cells, but revealed varying degrees of sensitivity to hyperthermia (MT-2 < MJ < HUT102) by 51Cr release assay. Hyperthermia did not cause immediate cell death as determined by the trypan blue exclusion test, but did cause substantial decreases in the numbers of heated cells within 2 days. The density of the cells began to increase thereafter, which was consistent with the results of the experiments labeling the cells with 3H-TdR after hyperthermia. When the cells were heated at 39-43 degrees C for 1-3 hr and then interacted with various LAK cell/ATL cell (E/T) ratios at 37 degrees C for 4 hr, total cytolysis of the cells increased in a synergistic and/or additive manner over that of the cells without hyperthermia. Prolonged incubation of the cells at high temperature did not necessarily cause a large increase in the interaction of LAK cells after hyperthermia. This augmentation of cytolysis by LAK cells after hyperthermia was not seen in normal peripheral lymphocytes. These results suggest that the combination therapy of hyperthermia and LAK cells may be more specific, useful, and effective for treating malignant lymphoma.

Synergistic effects of cytokine and hyperthermia on cytotoxicity in HT-29 cells are not mediated by alteration of induced protein levels

In this study, we investigated the mechanism of synergistic effects of cytokine and hyperthermia on cytotoxicity in HT-29. When cells were heated at 42 degrees C in the presence of recombinant human tumor necrosis factor (rhTNF-alpha), recombinant interferon-gamma (rhIFN-gamma), or in a combination of both, a synergistic increase in the cytotoxic effects of the respective drugs was observed. We hypothesized that alteration of cytokine or heat-induced polypeptides synthesis was responsible for a synergistic interaction between heat and cytokine. Five heat shock proteins (HSPs, M(r) 110,000, 100,000, 90,000, 70,000, and 28,000) were preferentially synthesized during chronic heating at 42 degrees C. In contrast, the synthesis of two proteins (M(r) 60,000 and 29,000) was induced by treatment with rhIFN-gamma (1,000 U/ml). Although the combination of chronic hyperthermia (42 degrees C) with TNF-alpha, IFN-gamma, or TNF-alpha + IFN-gamma increased cytotoxicity, alteration/induction of polypeptides was not correlated with the synergistical cytotoxic effects of cytokine and heat. Thus, the synergistic effects of cytokine and hyperthermia are not mediated through an induction of polypeptides.