Immunity: An Overview

Question 1

Innate Immunity is comprised of:

Answer 1

1. Epithelial barriers
2. Phagocytic leukocytes
3. Natural Killer Cells
4. Plasma proteins (complement)

Question 2

Adaptive Immunity is comprised of:

Answer 2

1. T-Cells (cell-mediated immunity)
2. B-Cells (humoral immunity)

Question 3

Innate immunity recognizes…

Adaptive Immunity recognizes…

Answer 3

Innate: Molecular patterns (PAMPs)

Adaptive: Epitopes on the antigen

Question 4

Innate Immunity function?

Answer 4

Provide primary defense against invading pathogens

Question 5

What are the phagocytic cells of innate immunity?

Answer 5

Macrophages and neutrophils

Question 6

How does the innate system get activated?

Answer 6

• Pattern Recognition Receptors (PRRs) recognize molecular patterns (PAMP) on bacteria, virus, fungal, or parosite pathogens
• This activates a series of proinflammatory (Nf-Kb) or anti-viral signaling pathways

Question 7

What are the vasoactive factors associated with innate immunity?

Answer 7

Substance P and Histamine

Question 8

Adaptive immunity function?

Answer 8

Provides antigen-specific defense

Question 9

How does an adaptive immune response get activated?

Antigen:

Epitope:

Answer 9

Antigen: A molecule that binds to an Antibody or T-cell receptor

Epitope: The specific portion of macromolecular antigen recognized by receptors expressed on lymphocytes

Question 10

Difference between receptors for B-cells and T-cells

Answer 10

B-cell receptor (antibody) recognizes epitopes on macromolecular proteins and lipid antigens

T-cell receptor recognizes epitopes on peptide fragments complexed with either an MHC class I or MHC class II presentation molecule

Question 11

Antigen presentation between the two types of T-cells

Answer 11

Cytotoxic = CD8+: MHC class-I restricted (goal = KILL)

Helper = CD4+: MHC class II restricted (goal = recruit/activate)

Question 12

Second signaling for CD4+ cells

Answer 12

CD40:CD40L

Question 13

5 Steps of T-cell Immunity

Answer 13

1. Recognition (intracellular organisms)
2. Clonal Expansion (IL-2 proliferates T-cells)
3. Differentiation (Effector vs. Memory cells)
4. Migration
5. Effector Functions

Question 14

Types of CD4+ T helper cells

Answer 14

TH1; TH2; TH17

Question 15

TH1

Cytokines produced:

Cytokines that induce this subset:

Immunologic reactions triggered:

Host Defense against:

Role in disease:

Answer 15

Cytokines produced: IFN-γ

Cytokines that induce this subset: IFN-γ, IL-12

Immunologic reactions triggered: Macrophage activation, stimulation of IgG antibody production

Host Defense against: Intracellular microbes

Role in disease: Immune-mediated chronic inflammatory diseases

Question 16

TH2

Cytokines produced:

Cytokines that induce this subset:

Immunologic reactions triggered:

Host Defense against:

Role in disease:

Answer 16

Cytokines produced: IL-4, IL-5, IL-13

Cytokines that induce this subset: IL-4

Immunologic reactions triggered: Stimulation of IgE production, activation of mast cells and eosinophils

Host Defense against: Helminthic parasites

Role in disease: Allergies

Question 17

TH17

Cytokines produced:

Cytokines that induce this subset:

Immunologic reactions triggered:

Host Defense against:

Role in disease:

Answer 17

Cytokines produced: IL-17, IL-22, chemokines

Cytokines that induce this subset: TGF-ß, IL-6, IL-1, IL-23

Immunologic reactions triggered: Recruitment of neutrophils, monocytes

Host Defense against: Extracellular bacteria, fungi

Role in disease: Immune-mediated chronic inflammatory diseases

Question 18

Function of B-cell response

Answer 18

Antigen-specific immune response to Extracellular Pathogens/ Antigens; Immune surveillance

Question 19

B-cell antibody isotypes

Answer 19

IgM, IgG, IgA, IgE

Question 20

Antibodies

IgM:

IgG:

IgA:

IgE:

Answer 20

IgM: Low affinity; activates classical complement pathway

IgG: Neutralize microbes/toxins; opsonization; activates classical complement pathway; antibody dependent cellular cytotoxicity (ADCC)

IgA: Mucosal transport; neutralize mucosal microbes/toxins

IgE: Allergy (mast cell degranulation); ADCC of parasites

Question 21

What are the purpose of complements and what are the three pathway types?

Answer 21

A system of serum and cell surface proteins that interact with one another and other molecules to generate effectors of innate and adaptive immune system

• Alternatative pathway
• Classical pathway
• Lectin pathway

Question 22

Live attenuated vaccine vs. Inactivated vaccine

Answer 22

Live attenuated: Micro-organism is modified to decrease pathogenicity - mainly induces T-cells

Inactivated: Pathogen is inactivated w/heat or chemicals but retains an immunologic epitope on surface - mainly induces B-cells

Question 23

Replication of adaptive T and B cells as a result of vaccination leads to: (2)

Answer 23

1. Antigen-specific immune destruction of the antigen
2. Creation of memory cells, prepared for activation upon reinfection

Question 24

Hypersensitivity

Type I:

Type II:

Type III:

Type IV:

Answer 24

Overactive or injurious immune reactions

Type I: Immediate → IgE and Mast cells

Type II: IgG, IgM mediated

Type III: IgG-complement immune complex

Type IV: Delatyed hypersensitivity → T cell-mediated