This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Tumor Antigens”.
1. Where are tumour antigens released?
a) Bloodstream
b) Bone marrow
c) Liver
d) Spleen
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Explanation: Tumour antigens are usually released in the blood stream. These antigens are associated on the surface of tumour cells. Tumour antigens are almost structurally similar to the antigens that are associated with normal cells. There are some cases when these tumour antigens remain associated with the tumour cell surface without releasing in bloodstream.
2. What are the two major types of tumour antigens?
a) Tumour-specific and Tumour-associated antigens
b) Tumour-associated and Tumour-generated antigens
c) Tumour-specific and Tumour-generated antigens
d) Tumour-generated and Tumour-developed antigens
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Explanation: Tumour antigens are classified in two major categories: 1) Tumour-specific antigens (TSAs): these are present on tumour cells only. They are produced due to physical, chemical and viral mutagens. They induce cell-mediated immune response by tumour-specific cytosolic T-cells; while 2) Tumour-associated antigens (TAAs): these are present on some tumour cells and also on normal cells. They are expressed on normal cells during fetal development. This classification is mainly based on their expression patterns and their specificity.
3. Tumour antigens are derivatives of which molecule?
a) Somatic cells
b) Cytosolic proteins
c) Oncogenes
d) Growth factors
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Explanation: Structural composition of normal antigens (associated with normal cell surfaces) and tumour antigens (associated with tumour cell surfaces) might be almost similar, however, their chemical composition differs to a greater extent. Normal antigens comprise of membrane proteins while tumour antigens consist of cytosolic protein derivatives.
4. Which virus causes cervical and liver cancer?
a) Oncovirus
b) Papillomavirus
c) Norwalk virus
d) Adenovirus
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Explanation: The DNA content of oncovirus causes cancer by inhibiting the activity of Ras and p53. The first proto-oncogene to be shown to turn into an oncogene is called Ras. Ras encodes an intracellular signal-transduction protein. In other words, Ras is one of the on and off switches in a major pathway that eventually leads to cell growth. Oncovirus inhibits this activity due to which there is uncontrollable growth of cells which in turn causes cervical of liver cancer.
5. Which of the following statement about Tumour-specific antigens is true?
a) They are not unique to tumour cells
b) They are associated with tumour cells only
c) Reactivation of embryonic genes takes place
d) They are present on normal cells during fetal development
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Explanation: Tumour specific antigens (also termed as TSAs) are specific only to tumour cells. Unlike tumour associated antigens they are not vulnerable to normal cells. This is one of the major differences between the two. TSAs are produced due to physical, chemical and viral mutagens. On the other hand, tumour associated antigens are not unique to tumour cells due to their commitment to normal cells. Reactivation of embryonic genes takes place as they encode oncofoetal proteins in tumour cells resulting in expression on fully differentiated tumour cells.
6. Tyrosinase is a tumour antigen found in which of the following tumour?
a) Germ cell tumour
b) Breast cancer
c) Melanoma
d) Bowel cancer
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Explanation: Tyrosinase helps in controlling the production of melanin. As it controls the production of melanin, it indicates that it is associated with skin cancer i.e., melanoma (also termed as malignant melanoma). It is termed as malignant because the tumour cells develop and grow uncontrollably which leads to skin cancer. Tyrosinase is an enzyme that can be obtained from bacteria, fungi or even virus if they enter the human body.
7. Which of the following is NOT a tumour specific antigen producing agent?
a) Methylcholanthrene
b) UV rays
c) Polyoma virus
d) Alpha-fetoprotein
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Explanation: Tumour specific antigens are specific to tumour cells. These tumour cells are developed due to overpopulation and uncontrollable growth of the cells. The tumour specific antigens produce due to some chemical, physical and viral agents like methylcholanthrene, UV rays and Polyoma virus respectively. These agents react irrespective of tissue and concentration. Their nature depends on the type of tissue damage and the seriousness of the uncontrolled process.
8. What does CTAG stand for?
a) Cancer-testis antigen
b) Cancer-test antigen
c) Cancer-test antibody
d) Cancer-testis antibody
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Explanation: Cancer-testis antigen are tissue differentiation antigens that are primarily expressed on germ cells of the testes and also fetal ovaries along with the trophoblast. CTAs are a group of proteins which develops in male germ cells in adults. CTAs correlate with tumour progressions. They are often present in melanoma, liver and lung cancer. Examples of CTAs are CTAG1B and MEGEA1.
9. Which tumour antigen is found in breast cancer?
a) CA-125
b) Tyrosinase
c) MUC-1
d) RAS
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Explanation: Breast cancer develops from the tissues of the breast. The most visible symptoms from X-ray are lump in breast, change in breast size and visible dents of the skin around the breast. During this breast cancer, the tumour antigen that comes in action is MUC-1 which is the abbreviation of Mucin 1. It is a cell surface associated antigen. MUC-1 has a core protein mass of 120-225 kDa. Glycosylation takes place due to which the protein mass gradually increases.
10. Which of the following Oncovaccine was approved for kidney cancer?
a) Oncophage
b) Provenge
c) Sipuleucel-T
d) BCG
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Explanation: Oncophage vaccine was first developed by an American pharma company and was approved by Russia for the diagnosis of kidney cancer. This vaccine is considered to be one of the milestones as it was the first vaccine developed in order to treat the early stages of kidney cancer. This vaccine was made from a patient’s tumour by carrying out the extraction of heat shock proteins.
Sanfoundry Global Education & Learning Series – Immunology.
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