Overcoming suppression of antitumor immune reactivity in tumor bearing rats by treatment with bleomycin

We investigated the immunological role of bleomycin (BLM) in the treatment of KMT-17 fibrosarcoma-bearing rats. We were able to detect antitumor immune reactivity by using a mixed-lymphocyte tumor culture in spleen cells shortly after the transplantation of a KMT-17 fibrosarcoma in syngeneic Wistar...

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Bibliographic Details
Published in:Cancer research (Chicago, Ill.) Ill.), 1988-12, Vol.48 (23), p.6658-6663
Main Authors: XU, Z.-Y, HOSOKAWA, M, MORIKAWA, K, HATAKEYAMA, M, KOBAYASHI, H
Format: Article
Language:English
Subjects:
Animals
Antineoplastic agents
Biological and medical sciences
Bleomycin - pharmacology
Chemotherapy
Cytotoxicity, Immunologic - drug effects
Female
Macrophages - immunology
Medical sciences
Neoplasms, Experimental - immunology
Pharmacology. Drug treatments
Rats
Rats, Inbred Strains
Spleen - immunology
T-Lymphocytes, Regulatory - drug effects
T-Lymphocytes, Regulatory - immunology
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Summary:We investigated the immunological role of bleomycin (BLM) in the treatment of KMT-17 fibrosarcoma-bearing rats. We were able to detect antitumor immune reactivity by using a mixed-lymphocyte tumor culture in spleen cells shortly after the transplantation of a KMT-17 fibrosarcoma in syngeneic Wistar King Aptekman/HMK rats. The reactivity declined following the progression of the tumor and was completely inhibited 11 days after the tumor transplantation. After the 11th day, however, spleen cells from BLM-treated KMT-17-bearing rats demonstrated higher antitumor immune reactivity. This result corresponds to those we obtained from an in vivo tumor-neutralizing assay (Winn assay). Macrophages from untreated tumor bearers were unable to inhibit the immune reactivity against KMT-17 cells in the mixed-lymphocyte tumor culture. Neither the tumor-bearing state nor the BLM treatment seemed to have any significant influence on another macrophage function, the antigen-presenting cell activity. However, a T-enriched fraction from untreated KMT-17 bearers showed a definite suppression activity on the generation of cytotoxic T-lymphocyte activity against KMT-17 tumor in the mixed-lymphocyte tumor culture; in contrast, no T-suppressor activity could be detected in the same fraction taken from BLM-treated tumor bearers. Our investigation suggests that BLM eliminates the tumor-specific T-suppressor activity without having any influence on responder T-lymphocytes in the cell-mediated antitumor immune reactivity.
ISSN:0008-5472
1538-7445