Immunology

Question 1

What is immunology?

Answer 1

a branch of biomedical sciences concerns with immunity or immune system
study of host defence against infection and disorders of the immune system

Question 2

What is the immune system?

Answer 2

a complex network of organs, tissues, cells and molecules that protect the body against infections and other diseases

Question 3

What are the organs and tissues of the immune system?

Answer 3

bone marrow
spleen
thymus
tonsils
mucous membranes
skin
lymphatic vessels
lymph nodes

Question 4

What are the cells of the immune system?

Answer 4

lymphocytes (T-cells, B-cells and NK cells)
granulocytes (neutrophils, eosinophils and basophils)
monocytes/macrophages

Question 5

What is immunity?

Answer 5

ability of the body to prevent invasion of pathogens (such as viruses, bacteria and fungi)

Question 6

Describe innate (non-adaptive) immunity.

Answer 6

first line immune response (present at birth)
relying on mechanisms that exist before infections
rapid (within minutes) but non-specific
inflammation

Question 7

Described acquired (adaptive) immunity.

Answer 7

second line immune response
T-cells and B-cells involved
developed from immunological memory

Question 8

What are the cells involved in innate immunity?

Answer 8

natural killer cells
dendritic cells
mast cells
neutrophils
basophils
eosinophils
macrophages

Question 9

What is the role of natural killer cells?

Answer 9

cytotoxic, kill infected cells and cancer cells

Question 10

What is the role of dendritic cells?

Answer 10

antigen-presenting, important to acquired immunity

Question 11

What is the role of mast cells?

Answer 11

rich in histamine and heparin, possess antibacterial and antiparasitic functions

Question 12

What is the role of neutrophils?

Answer 12

patrol for microbial infection and one of the first responders to the site of inflammation

Question 13

What is the role of basophils?

Answer 13

fight parasite infections and mediate allergic reactions

Question 14

What is the role of eosinophils?

Answer 14

possess antibacterial and antiparasitic functions

Question 15

What is the role of macrophages?

Answer 15

phagocytosis and present antigens along with dendritic cells

Question 16

What are DAMPs?

Answer 16

damage-associated molecular patterns
-endogenous molecules released from damaged and dying cells during infection and inflammation, such as high mobility group box 1 protein (HMGB1) and heat shock proteins (HLPs)
-interacting with pattern recognition receptors (PRRs)

Question 17

What is detecting missing-self?

Answer 17

recognizing molecules expressed in healthy cells but not in infected cells/pathogens
inhibiting innate immune response against host cells/tissues
mainly via NK cells

Question 18

What is MHC?

Answer 18

major histocompatibility complex, essential for acquired immunity

Question 19

Describe MHC class I.

Answer 19

HLA-A, HLA-B, HLA-C
identified in all nucleated cells
present normal self-antigens and foreign pathogen antigens to cytotoxic T cells

Question 20

Describe MHC class II.

Answer 20

HLA-DP, HLA-DM, HLA-DOA, HLA-DOB, HLA-DQ, HLA-DR
identified in macrophages, dendritic cells and B cells
present foreign pathogen antigens to T helper cells

Question 21

What is the structure of MHC class I and class II?

Answer 21

class I:
-heterodimer
-antigen binding pocket is on alpha unit (smaller than II)
-anchor attached to alpha unit
class II:
-binding pocket is on units and larger
-anchor is attached to both units

Question 22

What are the two types of acquired immunity?

Answer 22

cell mediated immunity
humoral immunity

Question 23

Describe cell mediated immunity.

Answer 23

antigen-specific cytotoxic T cells
release cytokines in response to the antigen
do not involve antibodies
kill infected cells

Question 24

Describe humoral immunity.

Answer 24

B cells
mediated by secreted antibodies
attack and neutralize antigens outside cells
prevent microbial penetration into body cells

Question 25

Where are T-cells made and matured?

Answer 25

bone marrow: hematopoietic stem cells --> lymphoid progenitor cells (migrate to thymus) thymus: lymphoid progenitor cells --> functional T-cells with specific markers (such as TCR, CD4 and CD8)

Question 26

Differentiate CD4 and CD8.

Answer 26

CD4: -helper T cells -secrete cytokines to stimulate the differentiation of B cells into plasma cells CD8: -cytotoxic T cells -bind and kill infected cells and cancer cells

Question 27

How are cytotoxic T cells activated?

Answer 27

activated by simultaneous interactions of surface molecules between cytotoxic T cell and APC --> T cell proliferation first activation signal: interaction between TCR of cytotoxic T cell and MHC I molecule of APC second activation signal: interaction between CD28 of cytotoxic T cell and CD80/CD86 of APC

Question 28

What are CD80 and CD86?

Answer 28

co-stimulators of T cell activation

Question 29

What are regulatory T cells (Tregs)?

Answer 29

specialized subgroup of T cells -CD4+, CD25+, FOXP3+ -different from helper T cells

Question 30

What is the role of Tregs?

Answer 30

supress immune response inhibit T-cell proliferation and cytokine production maintain immune homeostasis and self-tolerance prevent autoimmune disease promote cancer development and progression by inhibiting anticancer immunity within the TME

Question 31

What is the role of B-cells?

Answer 31

provide humoral immunity recognize specific antigens and differentiate into long-lived plasma cells plasma cells secrete antibodies binding to specific antigens on microbes destroy microbes and block them from entering into body cells some B-cells evolve into memory B-cells

Question 32

How are B-cells activated?

Answer 32

activated when B-cell receptor (BCR) binds to antigen T-cell dependent activation T-cell independent activation memory B-cell activation

Question 33

How are memory B-cells activated?

Answer 33

activated by different pathogens differentiate into long-lived plasma cells to secrete antibodies re-enter GCs to relinquish memory B cell pool

Question 34

Describe antibodies.

Answer 34

belong to gamma-globulin fraction of serum proteins Y-shaped five classes: IgA, IgD, IgE, IgG, IgM

Question 35

Describe IgA.

Answer 35

monomeric in serum dimeric in GIT and respiratory tract important first line of defence against infections inhibits bacterial growth and neutralize bacterial toxins neutralize viruses

Question 36

Describe IgD.

Answer 36

monomeric usually co-expressed with IgM activate B-cells, basophils and mast cells target mucosal antigens --> enhance mucosal immunity

Question 37

Describe IgE.

Answer 37

monomeric mediate type I hypersensitivity provide immunity against helminth infections

Question 38

Describe IgG.

Answer 38

~75% of serum antibodies --> main type of antibody monomeric produced after IgM bind different types of antigens such as viruses, bacteria, fungi four subclasses: IgG1, IgG2, IgG3 and IgG4 -IgG1, IgG3, and IgG4 can cross placenta -newborns: having same Ab as mother in first 6 months

Question 39

Describe IgM.

Answer 39

largest antibody pentameric first antibody produced for humoral immunity response respond to many antigens mainly produced from spleen and bone marrow may also present as hexamers --> physiological function unknown

Question 40

Describe mAb production via hybridoma technology.

Answer 40

fusion of B-cells and myeloma cells -B cells: antibody production -myeloma cell: longevity and reproduction