tumor immunology - COURSE: Medical Microbiology, PAMB...

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: Medical Microbiology, PAMB 650/720 - Fall 2008 Lecture 16 Tumor Immunology M. Nagarkatti Teaching Objectives: Introduction to Cancer Immunology Know the antigens expressed by cancer cells Understand the nature of immune response to tumors Study how cancers evade immune system Describe the approaches used in Immunotherapy Malignant Transformation: The proliferation of normal cells is carefully regulated. However, such cells when exposed to chemical carcinogens, irradiation and certain viruses may undergo mutations leading to their transformation into cells that are capable of uncontrolled growth, producing a tumor or neoplasm . A tumor may be 1) Benign, if it is not capable of indefinite growth and the host survives. 2) Malignant, if the tumor continues to grow indefinitely and spreads (metastasizes), eventually killing the host. This uncontrolled growth may be due to upregulation of oncogenes (cancer-inducing genes) and/or downregulation of tumor suppressor genes (that normally inhibit tumor growth often by inducing cell death). Evidence for existence of an immune response against tumors The following criteria serve as evidence that tumors can elicit an immune response. 1. Tumors that have severe mononuclear cell infiltration have a better prognosis than those that lack it. 2. Certain tumors regress spontaneously ( e.g. , melanomas, neuroblastomas).suggesting an immunological response. 3. Some tumor metastases regress after removal of primary tumor which reduces the tumor load, thereby inducing the immune system to kill the residual tumor. . 4. Although chemotherapy leads to rejection of a large number of tumor cells, the few tumor cells that evade the action of the drugs can outgrow and kill the host. However, the immune system may be able to mount an attack against the few tumor cells that are spared by the chemotherapeutic agent. 5. There is an increased incidence of malignancies in immunodeficient patients such as AIDS patients who are susceptible to Kaposi sarcoma and transplant patients who are susceptible to Epstein Barr virus (EBV)-induced lymphoma. 6. Tumor-specific antibodies and T lymphocytes (detected in cytotoxicity and proliferative response assays) have been observed in patients with tumors. 7. The young and the old population have an increased incidence of tumors. These members of the population often have an immune system that is compromised. 8. Hosts can be specifically immunized against various types of tumors demonstrating tumor Ags can elicit an immune response. 1
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This note was uploaded on 02/18/2010 for the course BIOL 2273 taught by Professor Trevorrook during the Spring '09 term at Adams State University.

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tumor immunology - COURSE: Medical Microbiology, PAMB...

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