Overview of Immunity

Question 1

Innate vs Adaptive immunity response

Answer 1

• Innate response: born with it and broad
• Acquired response: adaptive and specific

Question 2

Describe some aspects of innate immunity

Answer 2

• External barriers (1st)
  
  • Skin, mucous, stereocilia, pH, enzymes, microbiomes, etc
• Complements
  
  • ​enzymatically cleaved to form lytic (pore-forming) structures on infectious particles OR
  • serve as opsonins to facilitate phaogcytosis
• Phagocytosis
  
  • Monocyte/macrophage
  • neutrophils (PMNs)
  • Sometimes dendritic cells
• Non-phagocytic leukocytes: NK cells, eosinophils, basophils

Question 3

Acquired immunity components

Answer 3

• B lymphocytes produce antibodies that..
  
  • Help macrophages’ phagocytosis
  • Initiates complement cascade
• Helper T / CD4 T cells produce cytokines that activate toher cells
• Cytotoxic T / CD8 T cells produce perforin to lyse a target cell

Question 4

3 key points (adjectives) about the third line of defense

Answer 4

Adaptive: recognition & response

Specific: antigen-specific cell surface receptors

Memory: long-lived B and T memory cells produce a more efficient response

Self/non-self antigendiscrimination

Question 5

Benefits of immunological memory in acquired immunity (anamnestic response)

Answer 5

Faster

Greater conc of antibodies

Sustained antibody production

Affinity maturation (more specific anitbodies)

Question 6

Primary vs Secondary lymphoid organs and tissues

Answer 6

Primary: bone marrow & thymus

Secondary: lymph nodes & spleen

Question 7

All immune cells are derived from ___

Innate response is mostly derived from a common _____

Adaptive response is mostly derived from a common___

Answer 7

All are from bone marrow

Innate response is from a myeloid progenitor cell

Adaptive response is from a lymphoid progenitor cell

Question 8

B cells respond to __; whereas, T cells respond to ___

Answer 8

B cells respond to a native antigen (whole protein)

T cells respond to a processed antigen (epitope presented by an antigen-presenting cell gudied by surface holders called MHCs)

Question 9

What happens after a B cell responds to its native antigen (whole proteins)?

Answer 9

1. Bind antigen
2. Clonal selection & proliferation
3. Activation by Helper T cells
4. Differentiation into plasma cells or memory cells
5. Antibody (immunoglobulins) production by plasma cells

Question 10

B cell activation occur?

Answer 10

Germinal centers of the lymph node

Question 11

Antibody-mediated or humoral immunity

Answer 11

Mediated by B cells’ antibodies; can be transferred to a recipient w serum (passive transfer)

• Neutralization: block host cells’ receptors to prevent invasion
• Complement activation: neutrophil accumulation, lysis of target cells
• Opsonization: enhance phagocytosis
• Antibody-dependent cellular cytotoxicity (ADCC)

Question 12

What kind of organisms face antibody-mediated immunity? Cell-mediated immunity?

Answer 12

Extracellular organisms (e.g. blood-borne bacteria, protozoa, etc) -> antibody mediated immunity

Intracellular organisms (e.g. intracellular bacteria, viruses, protozoa) –> cell-mediated

Question 13

Cell-mediated immunity

Answer 13

Mediated by T cells and the substances they produce:

• IFN-y activates macrophages
• Reactive metabolic intermediates such as NO kill obligate intracellular pathogens
• CD8+ T cells bind and kill target cells

Question 14

What are cytokines?

Answer 14

Soluble mediators or msgers involved in immune regulation and pathophysiology:

• T-cell & B-cell activation
• Hematopoiesis
• Toxicity
• Inflammation

Question 15

Name the important Type 1, Type 2, pro-inflammatory, and anti-inflammatory cytokines

Answer 15

Type 1: IFN-y

Type 2: IL-4

Proinflammatory: TNF-a

Anti-inflammatory: IL-10

Question 16

B cell specificity

Answer 16

The B cell will put some antibodies on the surface and secretes others, but both have the same 2 antigen-binding sites on the tips ofthe Y

Question 17

T cell specificity

Answer 17

T cell receptor (TCR) has only one antigen-binding site and is only produced in a membrane-bound form.

It recognizes antigens in the form of MHC molecules/HLA: linear peptide associated w host molecules

Question 18

MHC1 is recognized by ____

MHC 2 is recognized by ____

Answer 18

MHC1 - CD8 cytotoxic

MHC2- CD4 helper

Question 19

Active vs Passive immunity

Answer 19

Active immunity: immunization w an antigen (e.g. vaccines, infection, booster); strongest type and can use humoral and/or cell-mediated immunity

Passive immunity: transfer of immunity between organisms (e.g. mother-to fetus, horse serum); however, too much will cause serum sickness when the recipient develops antibodies against the serum

Question 20

___ induce simmunity better than vaccination of passive immunity

Answer 20

infection

Question 21

Undesirable consequences of acquired immunity

Answer 21

Allergies

Autoimmune disease

graft rejection

Question 22

1. Which of the following is a feature of acquired immunity?
   a) Memory
   b) Specific
   c) Self/non-self discrimination
   d) Enhancement of innate immunity
   e) All are features of acquired immunity

Answer 22

All are features of acquired immunity

Question 23

The process of coating a particulate with antibody or complement to facilitate phagocytosis is called

Answer 23

Opsonization

Question 24

Which of the following cells are not parts of the cellular innate mechanisms of host resistance against infectious agents? a) Neutrophils b) Monocytes c) Endothelial cells d) Eosinophils e) Natural killer cells

Answer 24

Endothelial cells

Question 25

Which of the following cells are phagocytes? a) Neutrophils b) B lymphocytes c) Endothelial cells d) Eosinophils e) Natural killer cells

Answer 25

Neutrophils are phagocytes

Question 26

The 3 phases of an immune response in temporal order are:

Answer 26

Recognition→Activation→Effector Phase

Question 27

What is the main consideration in knowing when to give booster immunizations?

Answer 27

Boosters should be given when antibody titers are low.