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Biomedical subjects

T Hamaoka

Publications and source records attributed to T Hamaoka.

At least 343 records · Page 19Linked to original sources
PubMed1980

A novel immunization procedure involving pretreatment with cross-reacting steroid conjugated to a copolymer of D-glutamic acid and D-lysine for production of low cross-reactive antisera.

Anti-testosterone and anti-5 alpha-dihydrotestosterone antisera have been produced by pretreatment of mice with a cross-reacting steroid coupled to a copolymer of D-glutamic acid and D-lysine to inhibit production of cross-reacting antibodies before immunization with the specific steroid conjugated to a protein. 15 beta-Carboxyethylmercapto derivatives were used as haptens. The cross-reactivities of the anti-testosterone and anti-5 alpha-dihydrotestosterone antisera with 5 alpha-dihydrotestosterone and with testosterone were 0.49 and 13.5%, respectively.

Animals↗
PubMed1980

Augmented induction of tumor-specific resistance by priming with Mycobacterium tuberculosis (TBC) and subsequent immunization with PPD-coupled syngeneic tumor cells.

The present study investigates the augmenting effect of tuberculin- (PPD) reactive amplifier T cells on the induction of syngeneic tumor immunity. PPD-reactive helper (amplifier) T cell activity was generated in C3H/HeJ mice by appropriate immunization with heat-killed Mycobacterium (Tbc). Immunization of these Tbc-primed mice with PPD-coupled syngeneic X5563 tumor cells led to augmented generation of in vivo tumor-neutralizing activity contingent on the presence of PPD-reactive amplifier T cell activity. Splenic T cells from these mice exhibited potent tumor-neutralizing activity using Winn's assay, whereas spleen cells from mice not primed with Tbc before PPD-X5563 immunization failed to neutralize viable X5563 tumor cells. After establishing that the neutralizing activity was tumor specific and mediated by T cells, the applicability of this augmentation of tumor-specific immunity to an immunotherapy model was explored. Immunization with PPD-X5563 in the early stages of the tumor-bearing state induced potent anti-tumor activity sufficient to reject the growing tumor. Pretreatment of mice with cyclophosphamide or light x-irradiation (250 R), procedures that eliminate suppressor cell activity nonspecifically, before priming with Tbc further potentiated the anti-tumor activity under these conditions. Thus, the present study elucidates the augmenting effect of PPD-reactive amplifier T cells in the induction of tumor-specific immunity and provides an effective method of immunotherapy in tumor-bearing animals.

Animals↗
PubMed1980

Preventive effect of Propionibacterium acnes on metastasis in mice rendered tolerant to tumor-associated transplantation antigens.

The present study was carried out to investigate the preventive effect of Propionibacterium acnes (P. acnes) on metastasis formation of C3H/He mice which has been rendered tolerant to tumor-associated transplantation antigen (TATA) of syngeneic X5563 plasmacytoma. C3H/He mice inoculated intravenously (iv) with 10(6) 7000 R X-irradiated X5563 tumor cells 3 times at 4-day intervals. These pretreated mice could not develop immune resistance against X5563 tumor even after the appropriate immunization procedure. In these TATA-tolerant mice, enhanced metastasis associated with the development of visually apparent metastatic nodules in the spleens was observed after intradermal (id) implantation with viable tumor cells, even if the tumor was resected surgically 7 days thereafter. Administration of P. acnes to these TATA-tolerant mice appreciably reduced the metastasis formation. Although the growth of the id primary tumor was not affected by injection with P. acnes, the combined treatment of surgical resection of the primary tumor and P. acnes administration resulted in complete protection against metastasis in TATA-tolerant mice. These results unequivocally demonstrated that the administration of P. acnes is effective for preventing the outbreak of metastasized tumors, which are readily inducible in the TATA-tolerant state.

Animals↗
PubMed1979

Regulatory functions of hapten-reactive helper and suppressor T lymphocytes. III. Amplification of a generation of tumor-specific killer T-lymphocyte activities by suppressor T-cell-depleted hapten-reactive T lymphocytes.

2,4.6-trinitrophenyl (TNP)-reactive T-cell activities were raised in mice by immunization with TNP-isologous mouse gamma globulin. After establishing that TNP-reactive T lymphocytes can serve as amplifier cells for induction of killer T lymphocytes in allogeneic system, we explored the possibility of this hapten-reactive T-cell system to amplify tumor-specific killer T-lymphocyte activity in the syngeneic system. We utlized relatively weak immunogenic syngeneic plasmacytoma X5563 in C3H/He mice. Analysis of the TNP-reactive T-cell activities revealed that such T lymphocytes express the biological functions of both major subtypes of regulatory T cells, namely suppressors and helpers, and that TNP-reactive suppressor and helper T lymphocytes, respectively, differ in their relative susceptibility to specific inactivation by TNP conjugates of the nonimmunogenic D-amino acid copolymer, D-glutamic acid, and D-lysine (D-GL). By taking advantage of the relative susceptibility-difference to TNP-D-GL, selective inactivation of TNP-reactive suppressor T cells was induced by appropriate treatment with TNP-D-GL, and the generation of TNP-reactive helper T-cell activity was amplified. The supplement of augmented TNP-reactive helper T-cell activity to the system at the immunization with syngeneic X5563 with TNP-haptenation, resulted in a striking augmentation of induction of tumor-specific killer T-lymphocyte activity, and a considerable number of hosts survived after the challenge with lethal dose of viable tumor cells. Thus, appropriate manipulations designed to induce potent hapten-reactive helper T-lymphocytes provided the potential for a very effective mode of immunoprophylaxis against tumor.

Animals↗
PubMed1979

Prophylactic effect of BCG cell-wall skeleton on the tumor induction by 7,12-dimethylbenz[a]anthracene in mice: strain difference.

Prophylactic effect of repeated intravenous administrations of oil-attached BCG cell-wall skeleton (BCG-CWS) on the induction of tumor by 7,12-dimethylbenz[a]anthracene (DMBA) was investigated in various strains of mice. The subcutaneous injection of DMBA emulsified in oil induced squamous cell carcinoma in almost all of the strains of mice. Treatment of C57BL/6, BALB/c, and ddO strains with BCG-CWS with appropriate route and timing resulted in the retardation of DMBA-induced tumor development manifested by a prolonged latent period of tumor outgrowth. In contrast, the same BCG-CWS treatment of C3H/He and BTK mice was incapable in preventing such DMBA-induced carcinogenesis. Thus, the treatment with BCG-CWS was effective for preventing the DMBA-induced carcinogenesis in certain strains of mice, but the effectiveness varied depending on the strain. The implication of such a strain variationof the BCG-CWS effect on the prophylaxis of chemical carcinogenesis was discussed in the context of differences in the magnitude of immunopotentiation of the host by BCG-CWS.

9,10-Dimethyl-1,2-benzanthracene↗