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Smith’s General Urology - part 5

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Khối u cả thực nghiệm và tự nhiên có khả năng kích thích một phản ứng miễn dịch đặc hiệu kháng u. Quan sát này cho thấy là các protein nước ngoài (kháng nguyên) trên các tế bào khối u cổ điển đã được mô tả như là kết quả đáp ứng miễn dịch dịch thể và tế bào. | Immunology Immunotherapy of Urologic Cancers 18 Eric J. Small MD Both experimental and naturally occurring tumors are capable of stimulating a specific antitumor immune response. This observation suggests that there are foreign proteins antigens on tumor cells that classically have been described as resulting in humoral and cellular immune responses. However experimental models suggest that a T-cell cell-mediated response may be more important in the killing of tumor cells than a B-cell humoral response. A detailed description of the components of the immune system is beyond the scope of this chapter but certain features of the immune system as they pertain to diagnostic and therapeutic issues will be reviewed. Tumor Antigens Tumor antigens can be divided into tumor-specific antigens and tumor-associated antigens. Tumor-specific antigens are not found on normal tissue and they permit the host to recognize a tumor as foreign. Tumor-specific antigens have been shown to exist in oncogenesis models utilizing chemical physical and viral carcinogens but appear to be less common in models of spontaneous tumor development. The identification of tumor-specific antigens led to the theory of immune surveillance which suggests that the immune system is continuously trolling for foreign tumorspecific antigens. This theory is supported by the observation that at least some cancers are more common in immune-suppressed patients such as transplant patients or human immunodeficiency virus-infected individuals. However many cancers are not overrepresented in these patient populations. Furthermore spontaneous tumor models which more closely resemble human carcinogenesis appear to have a less extensive repertoire of tumor-specific antigens but instead have been found to express many tumor-associated antigens. Tumor-associated antigens are found on normal cells but either become less prevalent in normal tissue after embryogenesis eg alpha-fetoprotein AFP or remain present on normal .