This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “T-Cell Receptors and Signalling”.
1. Which organ from among the following is related to T cells?
a) Thymus
b) MALT
c) Bone marrow
d) Spleen
View Answer
Explanation: Thymus is the one that is related to T cells. Thymus is the site of maturation of T cells. Immatured T Cells are called thymocytes. After maturation until selection these are called naive T cells.
2. What are thymocytes?
a) Matured T cells
b) Immatured T cells
c) Matured B cells
d) Immaturd B cells
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Explanation: Immatured T cells are called thymocytes. Thymus is the site of maturation of T cells. These cells when matured are called naive or unprimed T cells until the selection process.
3. What is the selection process(es) which a matured T cell should go through to get activated?
a) Going through positive selection is enough
b) Going through negative selection is enough
c) Must go through both positive and negative selections
d) Going through any one of positive or negative selection process will do
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Explanation: A matured T cell should go through two selection processes. They are positive selection and negative selection. Any T cell which fails any one of the processes will be deleted/destroyed by thymus via apoptosis.
4. Immunological tolerance in T cells involves __________
a) Allowing unprimed T cells to pass through
b) Allowing to pass through but making them function less
c) Increasing the proliferation rate of T cells
d) Deletion of the T cells when failed
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Explanation: Immunological tolerance is nothing but the deletion of self-reactive T cells by negative selection. These involve variety of mechanisms to protect the T cells from autoimmune responses or diseases.
5. What are the two types of T effector cells?
a) T Helper and T Cytotoxic
b) T Helper and T Memory
c) T Cytotoxic and T Memory
d) T Memory and Pre-T cell
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Explanation: The two types of T effector cells are T Helper and T Cytotoxic cells. Also known as TH and TC cells. TH further has two subtypes, TH1 and TH2, each having it’s distinct function.
6. Which of the following interact with MHC I molecules?
a) CD4
b) CD8
c) CD19
d) CD25
View Answer
Explanation: CD8 co-receptors are expressed on T cytotoxic cells. They interact with the MHC I molecules and behave as the mediators of adaptive immunity. They perform cytotoxic functions.
7. Which of the following interact with MHC II molecules?
a) CD8
b) CD19
c) CD4
d) CD25
View Answer
Explanation: CD4 receptors are present on T helper cells. They recognize the antigenic peptides presented to MHC II molecules. These have a major role in intrathymic T cell selection.
8. Which receptors do alpha-beta T cells express?
a) CD25
b) CD4
c) CD8
d) CD3
View Answer
Explanation: Alpha-beta T cells express CD3 on the surface. This CD3 helps in activating the both naive CD4+ expressing T helper cells and naive CD8+ expressing T cytotozic cells.
9. T cells are capable of instant immune attack when they are______
a) Effector cells
b) Naive
c) Unprimed
d) Memory cells
View Answer
Explanation: When T cells are in their effector form, they can readily provide the immune function. The rate of the process where the antigens are presented and processed is really high.
10. What is the major difference between Cytotoxic T cells and Natural Killer cells?
a) Affinity
b) Specificity
c) Avidity
d) Presenting
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Explanation: The major difference between Cytotoxic T cells and Natural Killer cells is specificity. Cytotoxic T cells recognise the viral antigens present on the target cell. Natural killer cells cannot recognize them specifically.
11. Which of the following interleukins are secreted by T helper cells?
a) IL3, IL2, IL5
b) IL4, IL3, IL5
c) IL4, IL5, IL13
d) IL5, IL6, IL13
View Answer
Explanation: IL4, IL5, IL13 are secreted by T helper 2 cells. These interleukins help in the rapid induction of effector functions. IL4 not only just helps in the differentiation but is a compensatory cytokine in the TH2 response.
12. Compared to which receptor does the CTLA-4 binds to B7 with almost 20X more avidity?
a) CD3
b) CD4
c) CD8
d) CD28
View Answer
Explanation: CTLA-4 is an immune checkpoint which downregulates the immune responses. During the maturation and activation of T cells, B7 interacts with CTAL-4 instead of CD28. This happens when there is an uncontrolled proliferation and differentiation of the cells.
Sanfoundry Global Education & Learning Series – Immunology.
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