[Effects of separate administration of low-dose CDDP on antitumor immune reactivity for treatment of malignant glioma].
Recently, it has been reported that CDDP modifies the immune responses of tumor bearing hosts, but problem of the most appropriate treatment with CDDP to augment the host immunity remains unresolved. The purpose of this study was to determine the most advantageous administration of CDDP to increase both its cytotoxic effect and antitumor immune reactivity. Cell growth inhibition in vitro was assessed by MTT assay after treatment of U-251MG cells with various concentrations of CDDP for 24 or 120 hours. The results of this experiment showed that the growth of U-251MG cells in vitro was suppressed by CDDP in a dose-dependent as well as a time-dependent manner. Ten days after subcutaneous inoculation of human glioma cells, GL-9, in the rear flank of nude mice, they were assessed for growth suppression by CDDP. Totally, 20 ml/kg of CDDP was administered to each mouse; in one group (high-dose CDDP group), 5 ml/kg of CDDP on every fifth day, and in the other group (low-dose CDDP group), 2 ml/kg on every day. Measurement of the tumor volume in each group revealed no significant difference between the two groups in terms of the efficacy of tumor growth suppression. Twenty-one days after inoculation, we measured the splenic natural killer(NK) cell activity in each mouse. The results showed that NK cell activity was significantly increased in the low-dose cisplatin (2 ml/kg) group, and significantly decreased in the high-dose cisplatin (10 mg/ml) group, as compared to the control group. The results of our study suggest that the separate administration of low-dose CDDP is a useful treatment strategy for malignant glioma, because it increases the antitumor immune reactivity of hosts without decreasing the direct tumor cytotoxicity of CDDP.
Nishihara
T
T
Dept. of Neurosurgery, Ichihara Hospital, Teikyo University School of Medicine.
Tanaka
S
S
Murakami
M
M
Hirakawa
M
M
Nagashima
T
T
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000008:administration & dosage*; D003602:Cytotoxicity, Immunologic; D004334:Drug Administration Schedule; D005910:Glioma / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D007111:Immunity, Cellular; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D014407:Tumor Cells, Cultured / Q000187:drug effects
D002945:Cisplatin