Last edited: 8/8/2021
TOLL-LIKE RECEPTORS AND INTERFERONS
Immunology: Inflammation: Toll-like Receptors and Interferons
OUTLINE
I) TOLL-LIKE RECEPTORS
II) INTERFERONS
III) REVIEW QUESTIONS
IV) REFERENCES
I)
TOLL-LIKE RECEPTORS
● Proteins present in the cell membrane/vesicles inside the
cells that respond to foreign pathogens → elicit specific
responses
● Receptors expressed on WBCs like macrophages
● These receptors bind various pathogen associated
molecular proteins (PAMPs)
(1) PAMPs
o Detail viral nucleic acids (RNA and DNA)
o Lipopolysaccharide on bacteria
o Flagellin on bacteria
● When these receptors are activated by these PAMPs
o → triggers WBC to increase expression of nuclear
factor kappa beta (NfKB) →↑ expression of
proinflammatory cytokines such as:
 IL-1 Beta
 IL-18
 TNF-alpha
 Interferons
Medical Editor: Dr. Sofia Suhada M. Uzir
II) INTERFERONS
● Proteins made by virus infected cells
● Functions:
o Signal nearby host cells, let them know that there’s a
virus in the vicinity→ make antiviral peptides
o Alerting macrophages and natural killer cell to
become activated and proliferate
● Virus infects cells
o Triggers virus infected cell to express genes for
interferon production
● Interferon (IFN) types
o Alpha & beta IFNs
o Gamma IFNs
(A) ALPHA & BETA INTERFERONS
● Tell nearby healthy cells that there is a virus in the vicinity
● The nearby healthy cells than ↑ expression of antiviral
peptides
o If virus does infect healthy cells these antiviral
nucleases will destroy viral nucleic acids
● These IFNs also cause cells to ↑ expression of viral
antigens on MHC I molecules to activate cytotoxic T-cells
(B) GAMMA INTERFERONS
● These are made by natural killer cells and T helper type 1
cells when stimulated by IL-12 from activated
macrophages
● Actions:
o ↑ activity of macrophages → ↑ phagocytosis of virus
o ↑ activity of natural killer cells →↑cell killing of virus
infected cells
o ↑ expression of viral antigens on MHC II molecules for
antigen presentation to trigger ↑ antibody production
against virus
Figure 1. PAMPs recognition by TLRs [Hindawi]
Figure 2. Interferon functions [LSE]
TOLL-LIKE RECEPTORS AND INTERFERONS
IMMUNOLOGY: Note #1.
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III) REVIEW QUESTIONS
Which of the following IS NOT a proinflammatory
cytokines?
a. IL-1 beta
b. TNF-alpha
c. TNF-delta
d. IL-18
Concerning PAMPs, which is true?
a. The toll like receptors decrease its amount
b. Lipopolysaccharide on RNA is an example
c. Flagellin on virus is an example
d. Flagellin on bacteria is an example
Which of the following is not a type of interferons?
a. Alpha
b. Beta
c. Gamma
d. Delta
Which of the following is true concerning the
actions of interferons?
a. Increase activity of macrophages
b. Decrease expression of viral antigens on MHC II
molecules
c. Alerting nearby healthy cells to initiate apoptosis
d. Alerting nearby healthy cells to release macrophages
IV) REFERENCES
● Asa Cusack. The London School of Economics and Political
Science. Interferon functions [Digital image] LSE
● Ji-Yoon Noh, Suk Ran Yoon, Tae-Don Kim, Inpyo Choi,
Haiyoung Jung, "Toll-Like Receptors in Natural Killer Cells and
Their Application for Immunotherapy", Journal of Immunology
Research, vol. 2020, Article ID 2045860, 9 pages, 2020.
[Digital image] https://www.hindawi.com/journals/jir/2020/2045860/
● Le T, Bhushan V, Sochat M, Chavda Y, Zureick A. First Aid for
the USMLE Step 1 2018. New York, NY: McGraw-Hill Medical; 2017
● Marieb EN, Hoehn K. Anatomy & Physiology. Hoboken, NJ:
Pearson; 2020.
● Boron WF, Boulpaep EL. Medical Physiology.; 2017.
● Urry LA, Cain ML, Wasserman SA, Minorsky PV, Orr RB,
Campbell NA. Campbell Biology. New York, NY: Pearson; 2020.
● Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL,
Loscalzo J. Harrison's Principles of Internal Medicine. New York
etc.: McGraw-Hill Education; 2018.
● lberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P .
Molecular Biology of the Cell. New York, NY: Garland Science;
2002
● Murphy K, Weaver C. Janeway's Immunobiology. Garland
Science; 2016
● Doan T, Melvold R, Viselli S, Waltenbaugh C. Immunology.
Lippincott Williams & Wilkins; 2012
● Levinson W. Review of Medical Microbiology and Immunology.
Lange; 2012
Regarding alpha interferons, which is true?
a. It is considered as the late acting interferons
b. It helps in stimulating macrophages
c. It works by attaching to gamma interferons
d. It helps in activating cytotoxic T-cells
Regarding gamma interferons, which is true?
a. It directly activates cytotoxic T-cells
b. It helps increase cell expression of viral antigens on
MHC I molecules
c. It is made by natural killer cells
d. It doesn’t increase the activity of macrophages
Interferons are special defense mechanism which
operates by
a. Binding to viruses
b. Binding to neighboring cells
c. Producing a long-lasting state of resistance
d. Inhibiting virus induced enzymes
Cytotoxic T-cells can be activated via which of the
following?
a. By reacting with budding viruses
b. By identifying virus peptides presented by antibodies
c. By identifying virus peptides presented by MHC I
d. By releasing complement
How are antibody producing cells stimulated?
a. Interacting with a virus short peptide
b. Interacting with a T helper cell
c. Interacting with a plasma cell
d. Interacting with a virus infected cell
Which of the following is a characteristic of toll-like
receptors?
a. Cytoplasmic pattern recognition receptors
b. Type 1 membrane proteins consisting of a
recognition and signaling domain
c. Highly conserved receptors involved in programmed
cell death
d. Promotes activation of the transcription factor NFAT
(nuclear factor of activated T cells)
CHECK YOUR ANSWERS
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IMMUNOLOGY: Note #1.
TOLL-LIKE RECEPTORS AND INTERFERONS