IMMUNOTHERAPY OF A MURINE COLON CANCER WITH SYNGENEIC SPLEEN-CELLS, IMMUNE RNA AND TUMOR-ANTIGEN

  • 1 January 1982
    • journal article
    • research article
    • Vol. 29  (1) , 107-112
Abstract
In combination with xenogeneic immune RNA (I-RNA) and tumor antigen (TA), syngeneic spleen cells inhibited the growth of a N-methyl-N-nitrosourethane-induced colon carcinoma (CT-26) in BALB/c mice. The sequential administration of 1 .times. 107 spleen cells, 1 mg of anti-CT-26 I-RNA and 0.4 mg of CT-26 TA resulted in a 20% survival rate of mice bearing established CT-26 tumors. Administration of the spleen cells only, I-RNA only or TA only was not effective in inhibiting tumor growth. When any 1 of the 3 agents was omitted, no anti-tumor effect was obtained. A higher dose (1 .times. 108) and a lower dose (1 .times. 106) of spleen cells decreased the anti-tumor effect of this combination therapy. A higher dose (2 mg) and a lower dose (0.5 mg) of I-RNA, as well as a higher dose of TA (0.8 mg) had no influence on the anti-tumor effect. A lower dose of TA (0.2 mg) in combination with spleen cells and I-RNA decreased the anti-tumor effect. When all 3 agents were administered at higher or lower doses, no anti-tumor effect was obtained. When mice bearing CT-26 tumors were treated with spleen cells, plus I-RNA directed against a syngeneic but antigenically different tumor (BP/B/5) and BP/B/5 TA, with spleen cells plus CT-26 I-RNA and BP/B/5 TA, or with spleen cells plus BP/B/5 I-RNA and CT-26 TA, no anti-tumor effect was observed. The anti-tumor responses observed were due to tumor-specific immune responses. In order to obtain growth retardation or regression of established CT-26 tumor transplants, the sequential administration of all 3 agents (spleen cells, I-RNA and TA) was required. The optimal doses of each agent were 1 .times. 107 spleen cells, 0.5 or 1 mg of I-RNA and 0.4 mg of tumor antigen. Tumor-specific immune reactions appeared to be involved.

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