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Flashcards in Immunology Deck (30):
1

Isolated Lymphoid Follicles

A single follicle consisting solely of B-cells with an overlying M-cell

*Differs from Peyer's patches because these are also found in the colon

2

Effector Cells in the GALT

B-cells from Peyer's Patch: Travel thru efferent lymphatic to mesenteric lymph nodes, into the blood stream, and back into the GI mucose

T-cells from Mesenteric Lymph Node: Leave and travel to gastric mucosa

3

Effect B/T-cell Homing

1. Effector lymphocytes express a4:B7 which will bind to MADCAM-1 on the endothelial cells of gastric vasculature

2. CCL25 secreted by the SI epithelium binds to CCR9 on effector lymphs causing them to move into the lamina propria

3. IELs express aE:B7 which binds to E-cadherin expressed by SI epithelium facilitating the movement of IELs

4

Isotype switching to IgA

TGF-B

5

Functions of secretory IgA

1. Export toxins in the lamina propria

2. Neutralize toxins in endosomes

3. Bind Ag on mucosal surface

6

Oral Immunization

=> IgA in GI tract (until colon) AND Mammary glands

7

Intranasal Vaccination

=> IgA in upper respiratory tract AND cervical-vagina mucosa

8

Cells of mucosal epithelia

CD8+ T-cells

*Activated effector cells predominate

9

Gut Tolerance

Refers to the primary fnxn of immune cells in the GALT to restrain and not constantly activate the immune response

10

CCR7

Molecule lost by naive T-cells when activated by Ag in the MALT; replace it w/ L-selectin

11

Paneth Cells

Found at the crypts of the small intestinal villi and secrete antimicrobial proteins

12

Best response to intracellular bacteria

CD4+ Th1-mediated => binds to macrophages inducing heightened ROS species formation, release of inflammatory cytokines, and increased B7 expression

*Innate response includes NK (IFN-y) activation of macs

13

Best Mechanism for Viral Defense

CD8+ mediated elimination of effected cells thru the release of perforins/granzymes and the binding of Fas-FasL

*Ab response is important before the virus is intracellular and after its release

14

Best response for Extracellular Pathogens

Mediated by Abs released from CD4+-Th2 cells; release Abs into the bloodstream from the lymph node that fnxn to:

1. Activate the classical complement pathway => Anaphylaxis, complement coating

2. Bind Ag and macrophages thru the FcR-y

3. Opsonization of bacteria

*CD4+-Th1 cells will also release IFN-y and TNF-a

15

Adaptive Immune Response to Protozoa

Intracellular => Cell-mediated immunity via Th1 activation of macrophages by IFN-y release

Extracellular => Ab release triggering lysis, opsonization, and complement activation

16

Adaptive Immune Response to Helminths

Mediated by CD4+-Th2 cells AND unique products released by CD4+-Th1 cells including:

1. IL-4- promotes isotypic switch to IgE

2 IL-5- activates eosinophils => release of MBP which kills parasites

3. IL-13- promotes the alternative activation of macrophages (will now compromise helminth vitality w/ granuloma formation) and increased epithelial mucous production

17

Best Response to Fungal Infection

Mediated by CD4+-Th1 cells: Activates innate immune responses

*Treg limits response to prevent collateral damage

*Th2 can limit the response leading to fungal persistence

18

Sialic Acid Residues

Present on the capsules of extracellular bacteria and inhibits complement activation via the alternative pathway

19

lkB

When bound, inhibits NfkB from activating transcriptional changes; some bacteria can promote IkB binding to inhibit host response

20

Septic Shock

Caused by the widespread activation of complement and release of IL-1, IL-12, and TNF-a

*Characterized by circulatory collapse and DIC

21

Antigenic Drift

Gradual mutations that occur to increase the virulence factors of viral antigens

E.g-drift in the hemagglutinin gene

22

Antigenic Shift

RNA segments are exchanged with a secondary host

=>Rapid change in the form of the protein product produced by a virus

23

Response to Plasmodium

Sporozites exist in the blood stream => Elimination by complement

Sporozoites infect liver cells => Eliminated by CD8+ T-cells

Merozoites exist in blood => Elimination by antibodies

24

Response to Leishmania

Exist largely in macrophages and can cause scarring and tissue damage

=>Response mediated by Th1

25

Overreaction to Parasites

-Can result in nephrotic syndrome due to deposition of immune complexes

- Cross-recognition of peripheral nerve tissue

-Hepatosplenomegaly

26

Long IgA1

Flexible, but susceptible to cleavage

(Opposite for IgA2)

27

Dendritic Cells in the absence of extracellular bacterial infxn

Secrete TGF-B which causes FoxP3 to be expressed in CD4+ cells turning them into Treg cells

28

Dendritic cells in early bacterial infection

Produce IL-6 which causes CD4+ cells to express RORyt causing CD4+ cells to become Th17 cells

29

PPARy

Protein that removes NFkB from the nucleus; can be activated by bacteria as a defense mechanism

30

Activators of PMNs

LTB4

C5a

IL-8

Bacterial peptides