Immunology: MCQs on Host Defense Mechanism

Multiple Choice Questions  on Host Defense Mechanism (Immunology)

1) Based on the principles of the ............................................. theory, each individual lymphocyte possesses a distinct membrane receptor tailored to a specific antigen. When the antigen binds to its corresponding receptor, it triggers an immune response targeted specifically against that particular antigen.
a) Clonal selection theory
b) Instructional theory
c) Selective theory
d) Germ theory

2) Immunity is the defense mechanism of the body that protects against foreign pathogens. The immunity can be classified into innate immunity and acquired immunity. 
Which of the following statements is FALSE concerning innate immunity?
a) It exhibits a broad specificity against foreign antigens.
b) It is present before exposure to antigens.
c) It has memory cells.
d) None of the above.

3) Which type of immunity develops after exposure to specific antigens?
a) Acquired immunity     
b) Innate immunity
c) Natural immunity    
d) Passive immunity

4) Which of the following is not an example of innate immunity?
a) The epidermis (skin)
b) Immune Cells 
c) Sebaceous Glands
d) Measles immunity

5) Lysozyme is an enzyme present in the tears and mucous secretion that cleaves
a) Lipopolysaccharides
b) Cellulose
c) Peptidoglycan
d) None of the above

6) Lipopolysaccharides located in the cell membrane of gram-negative bacteria are identified by ..................................., leading to the initiation of an inflammatory immune response.
a) Phagocytosis
b) Antibodies
c) Mucus lining
d) Toll-Like receptors (TLR-2)

7) The cardinal signs of inflammation are rubor (redness), tumor (swelling), calor (heat), and dolor (pain). 
Which of the following is the characteristic feature of inflammation response?
a) Vasodilation
b) Increased capillary permeability
c) Recruitment of phagocytosis
d) All of the above

8) Humoral immunity involves the production of:
a) Antibodies by B cells
b) Cytokines by T cells
c) Histamines by neutrophils
d) Memory cells by macrophages

9) The antigen-presenting cells (APCs) play a crucial role in the antibody-mediated and cell-mediated immune response. 
Which of the following is not the characteristic feature of APCs?
a) APCs internalize and degrade antigens
b) APCs present antigens to the T-cells via MHC-II molecules
c) APCs provide a co-stimulatory signal for T-cell activation
d) Excess co-stimulatory signals from APCs lead to hyperactivation of an immune response.

10) Which of the following is not the class of T cells?
a) T-helper cells
b) T-activator cells
c) T-suppressor cells
d) T-cytotoxic cells

11) Which of the following cells produces antibodies?
a) T-cells
b) B cells
c) Plasma cells
d) Memory cells

12) Which of the following is expressed in T cells that interact with antigen epitope?
a) T-cell receptor
b) T-cell antibodies
c) B-cell receptor
d) B-cell antibodies

13) Antibody functions as the effector of the humoral response by antigen binding and neutralizing it. The antigen can be eliminated by..............................................................................
a) Facilitating the antibodies update by phagocytes
b) Activating complements and inducing cell lysis
c) Preventing the binding and host cell attachment
d) All of the above

14) Which of the following immune cells are not derived from lymphoid progenitor cells?
a) B-cells
b) T-cells
c) Neutrophils
d)Natural Killer cells

15) The development of pluripotent hematopoietic stem cells into different cell types requires the expression of a different set of genes for lineage determination at appropriate time and order. Various transcription factor is required for the expression of these genes. 
Which of the following statement is TRUE?
a) GATA-1 is required for myeloid lineage
b) Oct-2 is required for B cell differentiation to plasma cells
c) Ikaros is required for erythroid lineage
d) None of the above

16) The different lineage of the lymphocytes can be distinguished by characterizing the expression of their membrane molecules called the cluster of differentiation (CD). 
Which of the following CD is only found in B-cells?
a) CD-4
b) CD-8
c) CD-32
d) CD-45

17) Which of the following CD molecule is present in both cell types of T cells (Th and Tc) and acts as a receptor for the co-stimulatory signal from APCs?
a) CD28
b) CD4
c) CD2 
d) CD45

18) Which of the following CD molecule is a signaling transduction molecule present in lymphoid lineage cells such as T-cells, B-cells, and NK?
a) CD2
b) CD4
c) CD28
d) CD45

19) Which of the following cell plays a crucial role in antibody-dependent cell cytotoxicity?
a) Macrophage
b) Natural Killer cells
c) B-cells
d) Dendritic cells

20) The tissue-specific macrophage-like tissues are essential for phagocytosis of the antigens. 
Which of the following cells are present in the kidney?
a) Mesangial cells
b) Kuffer cells
c) Histiocytes
d) Alveolar macrophages

21) Immunogens are antigens that can evoke an immune response. 
Which of the following is not an immunogen?
a) Protein
b) Lipopolysaccharides
c) Hapten
d) Polysaccharides 

22) The degree of immunogenicity generally depends on the degree of foreignness. 
Which of the following protein are highly conserved among species and have little immunogenicity when injected into cross-species?
a) Thyroglobulin
b) Collagen
c) Insulin
d)Bovine Serum Albumin

23) Although the degree of immunogenicity generally depends on the degree of foreignness, certain antigens/tissues are immunogenic against self-antigens. 
Name the organ/tissue doing this type of function? 
a) Kidney
b) Cornea
c) Heart
d) Collagen

24) Which of the properties of an antigen makes it poorly immunogenic?
a) Distant species origin
b) High molecular weight proteins
c) Heteropolymers
d) Homopolymers

25) B-cells have cell surface antibodies that serve as the recognition molecule, and T cell recognizes when these antigens are presented via MHC molecules. 
Some glycolipids are also recognized by T-cell when presented by a non-MHC molecule known as..................................
a) CD1
b) CD2
c) CD4
d) CD8

26) The discrete sites that are recognized by antibodies or T cells are called epitopes. 
Which of the following is TRUE regarding epitopes?
a) B cell and T cells recognize the same epitopes
b) B cell and T cells recognize different epitopes
c) Epitope contains only sequential amino acids.
d) Epitopes bind to the antibody with covalent bonding

27) The epitopes that are recognized by B-cells are known as B-cell epitopes. 
Which of the following is a true statement regarding the B-cell epitope?
a) they are generally hydrophilic amino acids present on the surface
b) they contain both sequential and conformational epitopes
c) they tend to present in the flexible region of the antigens
d) All of the above

28) The epitopes that are recognized by T-cells are known as T-cell epitopes. 
Which of the following is a true statement regarding the T-cell epitope?
a) the epitopes are recognized by T-cell as a trimeric complex of TCR, antigen, and MHC molecule.
b) antigen processing is required for its presentation by APC
c) amino acid sequences of T-cell epitopes are generally internal of a protein molecule
d) All of the above

29) Name the congenital defect of thymus development that can lead to T-cell deficiency
a) Graves disease
b) Anaphylaxis
c) DeGeorge's syndrome
d) All of the above

30) Severe Combined immunodeficiency disorder (SCID) is a genetic disorder caused by a defective enzyme known as...................................................
a) Adenosine deaminase
b) Xanthine oxidase
c) Anaphyloticase
d) Lysozyme

Multiple Choice Questions Answer review
1- a)Clonal selection theory. According to the clonal selection theory, each lymphocyte has a unique membrane receptor specific to a particular antigen. When the antigen binds to its corresponding receptor, it initiates an immune response specifically directed against that antigen. 

2- c)It has memory cells. Innate immunity is the body's first line of defense against infections and does not involve memory cells. It provides a general, non-specific defense against a wide range of pathogens and is present from birth, providing immediate protection without the need for prior exposure to specific antigens.

3-a) Acquired immunity. Also known as adaptive immunity, it is a type of immunity that develops in response to exposure to specific antigens. Unlike innate immunity, acquired immunity is highly specific to particular pathogens or antigens.

4-d) Measles immunity. It is an example of acquired immunity is when a person develops immunity to a specific pathogen after being exposed to it or through vaccination.

6-d)Toll-Like Receptors (TLR-2). These are a specific type of innate immune system receptor that plays a crucial role in recognizing various microbial components, such as lipoproteins and lipopeptides from bacteria and other pathogens.

7-d)All of the above
8-a) Antibodies by B cells
9-d)Excess co-stimulatory signals from APCs lead to hyperactivation of an immune response
10-b) T-activator cells
11-c) Plasma cells
12-a)T-cell receptor
13-d)All of the above
15-b) Oct-2 is required for B cell differentiation to plasma cells
17)-a) CD28
19-b)Natural Killer cells
20)-a) Mesangial cells
23)-c) Heart
26)-b)B cell and T cells recognize different epitopes
27)-d)All of the above
29)-c)DeGeorge's syndrome
30)-a)Adenosine deaminase


  1. How can TLR-2 recognize LPS? I thought was TLR4

    1. TLR4 is predominant receptor that recognizes LPS but several studies have highlighted that the biological activity of some LPSs is not restricted to TLR4. ( See Reference: In the question above, TLR2 is the best answer among the choices.
      Thank you for commenting


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