A Study Of Tumor Antigen Activity Of The Vegetable Protein

Objective: Tumors have become one of fatal diseases for mankind. For the treatment of tumor, biological therapy is a new solution. It may be the 4th therapeutic method after operation, chemical-therapy and radio-therapy for cancer. Tumor cells developed from normal cells, so the antigenicity for self immune system is weak, or its specificity is not eminent in general. As a result, it can not induce a effective anti-tumor reaction. Human has a accurate surveillance system, but tumor cells often escape the immune attack. And the immune system gives rise to immuno-tolerance to the tumor antigen. So tumor cells proliferate, multiplicate and metastasize till death of the body. Tumor antigen is the core of tumor immuno-therapy. So promoting immuno-genicity of tumor cell, breaking body's immuno-tolerance and producing efficient tumor vaccine are the researching focus for immuno-therapy now. By the theory of biologic evolution, different organisms exist homologous genes when the nature evolves from the lower grade to the higher grade. And the farther is the relation between the two organisms, the stronger the immunogenicity is. We used the homologous proteins (vegetable protein extracted from a lower plant)between species to elevate immunogenicity and overcome self-immune tolerance to tumor cells.Methods: (l)When lymphocyte is stimulated by antigen, cell's DNA will synthesize and need some precursors of DNA. 3H-TdR as a specific precusor of DNA labeled with 3H, can be used to detect cell's proliferation by isotopic method. We cultured human peripheral blood lymphocytes (PBL) with the vegetable protein and 3H-TdR for 72 hours. The celles were harvested by the aid of cell harvester and the radioactivity of lymphocyte was measured and stimulation index(SI) was calculated. By the SI, we analysed whether the vegetable protein could specificly stimulate the lymphocyte of tumor patients to proliferation and verified its tumor antigenicity. (2)Chloramine-T which is a mild oxidizer can oxide I" to I+. The latter can combine with tyrosine. Through this way, we obtained antibody of the vegetable protein labeled by I3II. We injected the antibody into Lewis mice suffered from Lung Cancer, and radioactivity of different tissues was measured in different time(12h, 24h, 48h, 72h) after injecting and biological distribution of this antibody was observed in the mouse's organs to find if it could combine with the tumor cell significantly.Results: (1) The vegetable protein significantly stimulated esophageal(cardic) cancer patients' lymphocytes to proliferation. The SI of early esophageal(cardic) and of intermediate or late cancer patients (3.88+1.25 and 3.01 ?0.75) were higher than that of normal persons( 1.03 ?0.26 ). (PO.05).(2) The antibody of the vegetable protein had a different affinity to the mouse's organs and tumor tissues. Radioactivity of tumor tissue was far higher than that of the other's tissues(heart liver spleen kidney muscle). The %ID/g of tumor tissue was 3.08+0.29 2.85+0.42 2.97+ 0.38 and 2.76+0.45 respectively in 12h, 24h, 48h and 72h after injected the antibody. This results indicated that the antibody of vegetable protein could combine with tumor cell specificly.Conclusion: The vegetable protein has characteristics of tumor common antigen. This activity can be used clinical for tumor early diagnosis and specific active immuno-therapy. Its antibody may be used for directed therapy in near future.