Lecture 5 + 6

Question 1

When complement is activated, what happens?

Answer 1

opsonization, pro-inflammatory, chemotaxis, eliminate bacteria/microbes

Question 2

What is the complement sys?

Answer 2

A cascade of protein molecules that acts as an alarm & a weapon against infection, especially bacterial infection. Has the capacity to lyse cell membranes to microbes.

Question 3

What are the 3 modes of activation of the complement system?

Answer 3

1) Classical pathway
2) Alternate or properdin pathway
3) Mannose-binding protein

Question 4

What activates the classical pathway?
The alternate or properdin pathway?
The mannose-binding protein?

Answer 4

Antigen or antibody complex
Bacteria and their products binding to lectins (ex. C3b/factor B or D)
The binding of sugars on the bacterial cell.

Question 5

The three activation pathways of complement converge at a common _____________, the activation of the __ component. Then, _________ of pathogens, _____ of pathogens or __________ of inflammatory cells occur.

Answer 5

junction point; C3; opsonization; killing; recruitment

Question 6

The complement reaction starts with an __________. Complement components are designated by numerals (_____).
C1-C9 is activated by __________, then will be designated as “__” fragment and/or “__” fragment

Answer 6

enzyme cascade; C1-C9; cleavage; a; b

Question 7

In the classical pathway there are 2 antibodies that can be involved: ________. They are able to bind _____ and then undergo a change that allows _________ to bind (conformation change).

Answer 7

IgG or IgM; antigen; complement

Question 8

Classical pathway: C4b and C2b is referred as ___________. When you add C3b to C4b + C2b complex, it produces ___.

Answer 8

C3 convertase; C5

Question 9

The alternate pathway is activated directly by ________________ and their components (e.g., ________, ________________), as well as other factors.

Answer 9

bacterial cell surfaces; endotoxin; microbial polysaccharides

Question 10

The initial activation of the alternate pathway is mediated by __________ binding to ___ and then with properdin factor __, which splits factor __ in the complex to yield the __ active fragment that remains linked to ___ (activation unit).

Answer 10

properdin factor B; C3b; D; B; Bb; C3b

Question 11

What are the 3 antigen presenting cells in the body?

Answer 11

Dendritic cells, macrophages and B cells

Question 12

Cytotoxic T cells can only recognize _____.

Answer 12

MHCI

Question 13

CD represents what?

Answer 13

Clusters of differentiation

Question 14

T-cell surface markers are… Required for…?

Answer 14

molecules by which we can identify T-cells and divide them into subsets. They are required for interaction with APC and for antigen recognition.

Question 15

What are the attributes of Adaptive Immunity? (4)

Answer 15

Specificity
Memory
Ability to distinguish between self and non-self
Involves T and B cells

Question 16

What are the types of adaptive immunity?

Answer 16

Antibody-mediated immunity (involves B lymphocytes) and cell-mediated immunity (involve T lymphocytes)

Question 17

Where are B and T lymphocytes present in?

Answer 17

Present in blood, lymph, lymphoid tissues such as spleen, lymph nodes etc.

Question 18

CD4 T-helper (TH) lymphocytes recognize what? Activated and secrete what? 2 main subsets of TH cells are…?

Answer 18

They recognize antigen on the surface of APC in association with class II MHC molecules.
They are activated and secrete several cytokines.
TH1 & TH2

Question 19

What does TH1 produce?
TH2?

Answer 19

Cytokines of cell mediated immunity and inflammation e.g. IFN- γ , TNF- β , IL-3 and IL-2.
Cytokines that stimulate B-cells and immunoregulatory cytokines e.g. IL-4, IL-5, IL-6 and IL-10.

Question 20

Without TH, there is no __________________.

Answer 20

immune response

Question 21

Cytotoxic cells destroys ___________ by secreting _______ protein which punctures the __________ of an infected cell and causes __________.

Answer 21

infected body cells; perforin; cell membrane; apoptosis

Question 22

Large granular lymphocytes which lack most surface markers of B and T-cells. Function mainly in innate immunity, not MHC restricted & MHC I inhibits their killing functions.. This is ____________.

Answer 22

Natural Killer (NK) cells

Question 23

What are some ways that NK cells differ from CTLs? (4)

Answer 23

They are non-specific.
They act spontaneously without prior recognition or activation.
They do not require antigen presentation by MHC.
They destroy cells coated with antibodies: antibody dependent cellular cytotoxicity (ADCC).

Question 24

Give two types of antigen presenting cells.

Answer 24

Dendritic cells and macrophages.

Question 25

_______________ are the most efficient APCs, the main inducers of primary immune response, presenting antigen and activating native T-cells in the recognition phase.

Answer 25

Dendritic cells

Question 26

Describe macrophages.

Answer 26

Derived from myeloid stem cells in bone marrow, exist as free cells in blood (kupffer cells of liver), act as a link between innate and acquired immune responses.

Question 27

How does humoral immunity functions? (3)

Answer 27

Anti-toxins - neutralize bacterial toxins (e.g. diphtheria, tetanus)
Opsonization - antibodies attach to the surface of bacteria
Activation of B cells to make antibodies

Question 28

When opsonization occurs during humoral response, what happens? (4)

Answer 28

Act as opsonins & enhance phagocytosis.
Prevent the adherence of microorganisms to their target cells e.g. IgA in gut.
Activate the complement and lead to bacterial lysis.
Agglutination, leading to phagocytosis.

Question 29

State the 2 types and ex.s of immunity for both active and passive immunity.

Answer 29

Natural active immunity (acquired due to infection), artificial active immunity (due to vaccination)
Natural passive immunity (from mother to fetus through placenta, colostrum (milk), artificial passive immunity (injection of immune serum)

Question 30

What proinflammatory cytokines do macrophages produce?

Answer 30

IL-1, 6, 8, 12, TNF-alpha