抄録
Transplantable gliomas of C57BL/6J mice were used in order to investigate the influence of immunological resistance against tumors transplanted in the right parietal lobe. Immunization was induced by subcutaneous inoculation of approximately 1 mm3 of tumor grafts, irradiated by 3, 000 watt.sec/cm2 ultrasound or 3, 000 rad X-ray, once a week for 2 weeks to normal animals. Immunization was assured by tumor rejection or no growth 2 to 3 weeks after challenge of non-treated tumor implants. The rates of immunization against tumor were 67% by ultrasound irradiation and 45% by X-ray irradiation.
Passive transfer of resistance against the tumor was evaluated by IV injection of 1 × 108 spleen cells from immunized animals to normal isologous animals. The result showed a 40% rate of transfer. The rate of tumor growth transplanted in the brain was 71 % in immunized mice induced by subcutaneous inoculation with no significant difference from normal mice (81%). However, survival intervals after transplantation were significantly longer (P<0.01), ranging from 17.6 to 23.7 days. The tumor was more localized and showed more degeneration. Lymphocytic infiltration into the brain tumor was much less pronounced than subcutaneous tumor in immunized animals and there was no marked glial reaction. Focal lymphocytic accumulations were sometimes observed in perivascular spaces and in the meninges, but there were no clear differences from non-immunized tumor-bearing mice. The population of T-cells in the spleen and the mesenteric lymphnodes was evaluated by acid α-naphthyl acetate esterase (ANAE) stain in imprint preparations and in freshly snap-frozen (-80°C) and cryostat-cut specimens of the spleen, lymphnodes and brain tumors. ANAE stain reported by Mueller in 1975 demonstrated one or two positive dots in T-cells. T-cells in the spleen and lymphnodes increased but only a few were detected in the brain tumor of the immunized animals. Direct immunofluorescent studies with FITC-labelled anti-mouse Ig antibodies were applied to freshly snap-frozen and cryostatcut specimens. As a result, Ig-cotaining cells infiltrated the tissues around the subcutaneous tumor while a few penetrated the tumor tissues. Fluorescence was not marked on the cytoplasmic membrane of brain tumor of immunized animals but was positive in those of nonimmunized animals and was more marked in those animals which showed tumor growth in spite of induction of immunization, suggesting that the blocking factor described by Hellstrom was involved.
