MCQs on Immunology of T Cell Receptors (TCR gene structure and T cell Functions):

T cell receptors (TCRs) are cell surface proteins expressed on the surface of T cells, a type of white blood cell involved in immune responses. TCRs play a crucial role in recognizing and binding to antigens, which are foreign substances that activate the immune system.
The structure of TCRs consists of two protein chains, known as alpha (α) and beta (β) chains, which are linked together and form a heterodimer. Each TCR has a unique combination of α and β chains that determine its antigen specificity. The diversity of TCRs is generated through genetic recombination during T cell development, allowing T cells to recognize a wide range of antigens.
When a TCR encounters an antigen presented on the surface of an antigen-presenting cell (APC), such as a dendritic cell or macrophage, it binds to the antigen with high specificity. This binding interaction between the TCR and antigen is critical for initiating an immune response. The TCR signaling cascade is then activated, leading to T cell activation, proliferation, and differentiation into effector T cells that carry out specific immune functions.

1) T cells express a transmembrane protein that recognizes the peptide-loaded MHC (pMHC) to activate T cell-mediated immune response. 

The T-cell receptor is a...........................................................
a) protein of immunoglobulin superfamily
b) seven-transmembrane G protein family
c) tyrosine kinase receptor superfamily
d) None of the above

2) T cell receptor is a heterodimer consisting of...........................................
a) alpha and beta chain
b) gamma and delta chain
c) Both of the above
d) None of the above

3) Which of the following statement is FALSE regarding the T-cell receptor?
a) The alpha and beta chains of TCR are proteins of the immunoglobulin superfamily
b) Both alpha and beta chains consist of one variable domain and one constant domain
c) The TCR resemble Fab fragment of an immunoglobulin
d) The variable region is present in the C terminal region of the TCR

4) Which of the following is NOT the characteristic feature of T cell receptor
a) T-cell lineage Exclusivity
b) Affinity Maturation
c) The combinatorial joining of VDJ
d) Somatic hypermutation

5) Gamma/delta T cell receptors are present in a subset of T-cells and play role in the unconventional recognition of antigens. 

All of the following statements are correct, EXCEPT
a) The gamma/delta T-cell receptors are co-expressed with alpha/beta T-cell receptors
b) The gamma/delta T cell receptors undergo allelic exclusion when alpha/beta are expressed and vice versa
c) The gamma/delta T cell receptors recognize the phospholipid antigens
d) All of the above

6) Which of the following statement is true regarding the TCR gene organization and rearrangement?
a) The alpha & gamma genes consist of multiple variables (V), joining (J), and one constant gene
b) The beta & delta genes consist of multiple variables (V), diversity (D), joining (J) genes, and one constant gene.
c) Both of the above
d) None of the above

7) Which of the following process contribute to the diversity of TCR?
a) Somatic hypermutation
b) Junctional flexibility
c) Genetic recombination
d) None of the above

8) Once the TCR binds to the pMHC, the signal transduction mediates the T cell activation via CD3 molecules. The CD3 molecules consist of..................................................
a) Delta & Epsilon heterodimer
b) Gamma and Epsilon heterodimer
c) Zeta homodimer
d) All of the above

9) The alpha/beta chain of TCR has three complementarity determinant regions CDR1, CDR2, and CDR3. 

Which of the following CDR binds to the antigen peptide?
a) CDR1
b) CDR2
c) CDR3
d) All of the above

10) Which of the following is NOT the function of the T-cell receptor?
a) Antigen Recognition
b) Facilitate binding of co-receptor
c) Serve as the signal transducer
d) Induce signal transduction via a CD3 protein complex

11) Which of the following CD3 molecule is required for assembly of TCR-CD3 complex into the plasma membrane?
a) Gamma
b) Delta
c) Epsilon
d) Zeta

12) Which of the following protein of the TCR/CD3 complex do not consist of the ITAM domain required for signal transduction?
a) alpha/ beta chain of TCR
b) gamma/epsilon heterodimer of the CD3 complex
c) delta/epsilon heterodimer of the CD3 complex
d) Zeta homodimer of the CD3 complex

13) Which of the following subunits have three ITAM domains?
a) Gamma
b) Delta
c) Epsilon
d) Zeta

14) In addition to the TCR-CD3 complex, the T cell activation requires the engagement of co-receptors with the MHC of the antigen-presenting cells. Which of the following co-receptor binds to MHC-I APC
a) CD4
b) CD8
c) CD20
d) None of the above

15) In addition to the TCR-CD3 complex, the T cell activation requires the engagement of co-receptors with the MHC of the antigen-presenting cells. Which of the following co-receptor binds to MHC-II APC
a) CD4
b) CD8
c) CD20
d) None of the above

Multiple Choice Answers Review:
1-a) protein of immunoglobulin superfamily
2-c) Both of the above
3-d) The variable region is present in the C terminal region of the TCR
4-d) Somatic hypermutation
5-a) The gamma/delta T-cell receptors are co-expressed with alpha/beta T-cell receptors
6-c) Both of the above
7-b) Junctional flexibility
8-d) All of the above
9-c) CDR3
10-c) Serve as the signal transducer
11-d) Zeta
12- a) alpha/ beta chain of TCR
13-d) Zeta
14-b) CD8
15-a) CD4