54 Questions
What are tumour antigens?
Proteins, glycoproteins, glycolipids, or carbohydrates expressed on the tumour cell surface
How can tumour antigens be used for therapeutic purposes?
As targets for effective anti-cancer therapies
What can result in neoplastic transformation according to the text?
Genetic alterations in proto-oncogenes and tumour suppressor genes
How can tumour antigens be detected in the body?
Tumour antigens released into the bloodstream allow noninvasive detection
Which mechanism allows effector cells to recognize and kill tumour cells through ADCC?
Antitumour antibodies binding to NK cells or macrophages
What is a strategy of evasion employed by tumour cells?
Selective outgrowth of antigen-negative variants
What is a mechanism used by tumour cells to inhibit tumour immunity?
Tumour cells secreting immunosuppressive factors such as TGF-β and indolamine 2,3-dioxygenase
What is a goal of immunotherapeutic strategies?
Providing the patient with mature effector cells or antibodies that recognize and destroy tumours
What are LAK cells?
Antitumour lymphocytes generated in vitro
What is a method attempted to stimulate active immunity against tumour cells?
Administration of cytokines
What is Oncept Il-2 used for?
Immunotherapy
What do monoclonal antibodies raised against tumour antigens aim to do?
Carry substances directly to a tumour
What does the
Stimulating active immunity against tumour cells
What is the role of TGF-β and indolamine 2,3-dioxygenase in tumour immunotherapy?
Inhibiting tumour immunity
What is the purpose of vaccination with tumour antigens?
Stimulating active immunity against tumour cells
Which type of tumour antigens are recognized by CD8+ T cells?
Cytoplasmic proteins
Which of the following is an example of a tumour antigen?
Mutated RAS proteins
What is an example of a tumour antigen produced by an oncogenic virus?
FOCMA
What is the function of oncofoetal antigens?
Serve as tumour markers but not provoke protective immunity
Which of the following is considered a tumour antigen?
Gangliosides
What do tumours express that can be targeted for immunotherapy?
Cell type-specific differentiation antigens
What are the stages of the immune response to cancer?
Elimination, equilibrium, and escape
What is the dominant antitumour mechanism correlated with better prognosis in various cancers?
Cytotoxic T lymphocytes
Which cells are capable of destroying tumour cells without prior sensitization?
NK cells
What activates macrophages to kill tumour cells?
IFN-γ
How do B lymphocytes kill tumour cells?
By activating a local complement cascade
What is the main function of tumour antigens released into the bloodstream?
Allow noninvasive detection of tumours
What is the main purpose of using antibodies against tumour-restricted antigens in combination with sophisticated imaging techniques?
Localise tumours and detect metastases
Which of the following is a characteristic of tumour antigens that can serve as the target of effective anti-cancer therapies?
They are products of mutated genes
What is the relationship between neoplastic transformation and genetic alterations in proto-oncogenes and tumour suppressor genes?
Genetic alterations in these genes result in neoplastic transformation
Which of the following is an example of an oncofoetal antigen?
Tyrosinase
Which of the following is a tumour antigen produced by an oncogenic virus?
Feline-oncornavirus-associated cell membrane antigen (FOCMA)
Which of the following is a cell type-specific differentiation antigen?
CD20
Which immune response stage involves the activation of macrophages to kill tumour cells?
Elimination
Which of the following cells are capable of destroying tumour cells without prior sensitization?
NK cells
Which cells can incite both cell-mediated and humoral immune responses against tumour antigens?
B lymphocytes
Which of the following is a common method attempted to stimulate active immunity against tumour cells?
Vaccination with tumour antigens
Which of the following is a function of oncofoetal antigens?
Serve as tumour markers but not provoke protective immunity
Which of the following is a goal of immunotherapeutic strategies?
Enhance the body's immune response against tumour cells
Which of the following is a mechanism used by tumour cells to inhibit tumour immunity?
Production of immunosuppressive cytokines
Which of the following is considered a tumour antigen?
Gangliosides
Which of the following can be targeted for immunotherapy?
CD20
Which of the following is a strategy of evasion employed by tumour cells?
Selective outgrowth of antigen-negative variants
What is the purpose of Oncept Il-2 in tumour immunotherapy?
Stimulate the immune response against feline injection site sarcoma
What is the role of TGF-β in tumour immunotherapy?
Inhibit the immune response against tumours
What is the function of LAK cells in tumour immunotherapy?
Destroy tumour cells
What is the dominant antitumour mechanism correlated with better prognosis in various cancers?
Enhanced expression of MHC molecules
What is the purpose of vaccination with tumour antigens?
Stimulate active immunity against tumour cells
What allows effector cells to recognize and kill tumour cells through ADCC?
Binding of antitumour antibodies to NK cells or macrophages
What is the function of monoclonal antibodies raised against tumour antigens?
Recognize and destroy tumours
What are the stages of the immune response to cancer?
Antigen presentation, immune cell activation, tumour cell destruction
What is a method attempted to stimulate active immunity against tumour cells?
Vaccination with tumour antigens
What is the function of immunotherapeutic strategies in tumour therapy?
Provide mature effector cells or antibodies to recognize and destroy tumours
What is the purpose of the 'cancer vaccine' for canine malignant melanoma?
Destroy tumour cells
Study Notes
Tumour Antigens and Antitumour Effector Mechanisms
- Tumour antigens can be cytoplasmic proteins recognized by CD8+ T cells or aberrantly expressed cellular proteins recognized by CD4+ T cells.
- Examples of tumour antigens include mutates RAS proteins, mutated p53, tyrosinase, cancer-testis antigens, and prostate-specific antigen (PSA).
- Tumour antigens can also be produced by oncogenic viruses like Feline-oncornavirus-associated cell membrane antigen (FOCMA).
- Oncofoetal antigens are expressed in cancer cells and normal foetal tissues, serving as tumour markers but not provoking protective immunity.
- Altered cell surface glycolipids and glycoproteins, like gangliosides and mucins, are also considered tumour antigens.
- Tumours express cell type-specific differentiation antigens, such as CD20, which can be targeted for immunotherapy.
- The immune response to cancer goes through three stages: elimination, equilibrium, and escape.
- Cytotoxic T lymphocytes are the dominant antitumour mechanism, correlated with better prognosis in various cancers.
- NK cells are capable of destroying tumour cells without prior sensitization, activating apoptosis in the target cell.
- Macrophages may collaborate in antitumour reactivity, as IFN-γ, secreted by T cells and NK cells, activates them to kill tumour cells.
- B lymphocytes can incite both cell-mediated and humoral immune responses against tumour antigens, killing tumour cells by activating a local complement cascade.
Tumour Immunotherapy and Evasion of the Immune Response
- Antitumour antibodies can bind to NK cells or macrophages, allowing effector cells to recognize and kill tumour cells through ADCC.
- Tumour cells develop mechanisms to escape the immune system in immunocompetent hosts.
- Strategies of evasion include selective outgrowth of antigen-negative variants and loss or reduced expression of MHC molecules.
- Activation of immunoregulatory pathways by tumour cells can inhibit tumour immunity.
- Tumour cells secrete immunosuppressive factors such as TGF-β and indolamine 2,3-dioxygenase.
- Tumour antigens on the cell surface may be hidden from the immune system through antigen masking.
- Tumour therapy currently relies on chemotherapeutic inhibition of cell division and immunotherapy.
- Immunotherapeutic strategies aim to provide the patient with mature effector cells or antibodies that recognize and destroy tumours.
- Monoclonal antibodies raised against tumour antigens may be used alone or engineered to carry substances directly to a tumour.
- Antitumour lymphocytes generated in vitro, called LAK cells, are readministered to the patient.
- Various approaches to stimulate active immunity against tumour cells have been attempted, including vaccination with tumour antigens and administration of cytokines.
- Novel products like Oncept Il-2 for feline injection site sarcoma and the "cancer vaccine" for canine malignant melanoma have been introduced for immunotherapy.
Test your knowledge of tumour antigens and antitumour effector mechanisms with this quiz. Explore the various types of tumour antigens, immune responses to cancer, and the role of different immune cells in fighting tumour cells.
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