The combined effect of lymphokine activated killer cell and radiation therapy on rat brain tumor in vitro

X-irradiation to human malignant glioma cells enhances the cytotoxicity of autologous killer lymphocytes under specific conditions

PURPOSE

To clarify the effect of combining x-irradiation and human killer lymphocytes against autologous malignant glioma cells, we analyzed not only the alteration of surface antigen expression in irradiated tumor cells, but also the cytotoxic effects of human killer lymphocytes on the autologous tumor cells with and without x-irradiation.

METHODS AND MATERIALS

Six malignant glioma cell-lines (MG 1-6) established from each patient with a malignant glioma in our institute, and U87MG, were used as materials. They were irradiated by 0-50 Gy of X-rays, and the alternations of their human histocompatability leukocyte antigen (HLA), HLA-ABC, HLA-DR, -DP, -DQ, and FAS expressions were examined. Then, three sets of autologous natural killer (NK) cells, and autologous tumor-specific T lymphocytes (ATTL) were induced from the peripheral blood mononuclear cells (PBMCs) of three patients, and in vitro cytotoxic effects of these killer cells on the irradiated autologous tumor cells were analyzed.

RESULTS

Irradiation-enhanced HLA-DR, -DP, -DQ, and FAS expression in glioma cell lines with low p53 expression. However, there was no correlation between HLA-ABC expression and X-ray dose. After irradiation of the tumor cells, cytotoxicity was enhanced in four of six effectors; in particular, it was significantly elevated in two killer lymphocytes. It was speculated that the enhancing effect was influenced not only by the p53 status of the tumor, but also by the types of killer lymphocytes; the alteration of cytotoxicity in NK cells on irradiated tumor cells may be compensatory for alteration in ATTLs.

CONCLUSION

It was indicated that irradiation of malignant tumor cells enhanced killer cell-mediated cytotoxicity in autologous models under specific conditions. These basic data should contribute to clinical trials using local radiotherapy and systemic adoptive immunotherapy with killer lymphocytes.

Effects of lethal irradiation and cyclosporin A treatment on the growth and tumoricidal activity of a T cell clone potentially useful in cancer therapy

The TALL-104 cell line, originally derived from a patient with T cell leukemia, can be maintained indefinitely in culture in the presence of interleukin-2 (IL-2) and is endowed with a highly potent major-histocompatibility-complex (MHC)-non-restricted tumoricidal activity both in vitro and in animal models. The present study analyzes in detail the short- and long-term effects of irradiation and cyclosporin A (CsA) treatment on the growth and tumoricidal function of this T cell clone as compared to polyclonal lymphokine-activated killer (LAK) cell preparations from healthy donors. DNA and RNA syntheses by both TALL-104 and LAK cells were irreversibly arrested a few hours after irradiation with 40 Gy. However, 4-h 51Cr-release assays, performed on different days (day 1 to day 7) after irradiation, showed that the cytotoxic efficiency of TALL-104 cells against hematopoietic and solid tumor targets was only modestly reduced, whereas that of LAK cells was severely inhibited. Moreover, the cytotoxic responses to recombinant human IL-2 and IL-12, measured 18 h after irradiation and cytokine addition, were normal in the case of TALL-104 cells but were abolished in the case of LAK cells. Co-culture of IL-2- or IL-12-preactivated TALL-104 cells with a tumor target for 5 days in the absence of cytokines resulted in a lower efficiency of lysis, as compared to the non-irradiated effectors, especially if the initial stimulus was IL-12. These findings suggest the requirement of multiple cytokine stimulation for optimal expression of tumoricidal activity by lethally irradiated TALL-104 cells. CsA, while abrogating TALL-104 cell proliferation at the low dose of 0.5 microgram/ml, inhibited their cytotoxic function marginally only at high doses (100 micrograms/ml). By contrast, CsA reduced dose-dependently the cytotoxicity of LAK cells starting at very low doses (0.5 microgram/ml). CsA did not impair the ability of TALL-104 and LAK cells to produce interferon (IFN) gamma, tumor necrosis factor (TNF) alpha, and granulocyte/macrophage-colony-stimulatory factor (GM-CSF) in response to IL-2, IL-12, or tumor targets. Irradiation reduced drastically IFN gamma production by LAK, but not TALL-104 cells; release of TNF alpha and GM-CSF by either type of effector was inhibited by 10%-50%, depending on the stimulus. The high resistance and immunosuppressive drugs renders tis immortal T cell clone a potentially safe and effective reagent for new adoptive-transfer approaches to cancer in MHC-incompatible recipients.