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Flashcards in Immune System Deck (172)
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1

Innate Immunity
Receptor coding?
Response to pathogens is
Memory?
Cells involved?
Molecules involved?

Receptors that recognize pathogens are germline encoded
Response to pathogens is fast and nonspecific
No Memory
Neutrophils, Macs, Dendritic Cells, Natural Killer Cells (lymphoid origin)
Complement

2

Adaptive Immunity
Innate Immunity
Receptor coding?
Response to pathogens is
Memory?
Cells involved?
Molecules involved?

Receptors that recognize pathogens undergo V(D)J recombination during lymphocyte development
Response is slow on first exposure. Memory response is faster and more robust.
T and B cells
Antibodies

3

MHC
Stands for
Encoded by what gene?
Function
What does it bind?

Major Histocompatibility Complex
Human Leukocyte Antigen (HLA) gene
Presents antigen fragments to T cells and binds TCR

4

MHC I
Genes encoding it?
Binds what receptors
Which cells express it?
Where is antigen loaded
What kind of antigens?
What kind of immunity does it mediate?
What does it pair with and why?
Where is peptide groove?

HLA A, B and C
Binds TCR and CD8
All nucleated cells (not RBCs)
Antigen loaded in RER with mostly intracellular peptides
Mediates viral immunity
Pairs with β2 microglobins (aids in transport to cell surface)
Peptide groove in α chain

5

MHC II
Genes encoding it?
Binds what receptors
Which cells express it?
When is antigen loaded
What does it look like?

HLA DR, DP and DQ
Binds TCR and CD4
Expressed only on APCs
Antigen is loaded following release of invariant chain in an acidified endosome
α and β chains pair with peptide groove in between

6

Association with HLA A3

Hemochromatosis

7

Association with HLA B27

"PAIR"
Psoriasis, Ankylosing Spondylitis, IBDm Reiter's syndrome

8

Association with HLA DQ2/DQ8

Celiac

9

Association with HLA DR2

Multiple Sclerosis, Hay Fever, SLE, Goodpastures

10

Association with HLA DR3

DM type 1, Graves' Disease

11

Association with HLA DR4

RA, DM type 1

12

Association with HLA DR5

Pernicious anemia (B12 deficiency), Hashimoto's thyroiditis

13

Natural Killer Cells
What do they do?
What do they use to do it?
How are they unique?
What molecules enhance their activity?
When are they induced to kill?

Induce apoptosis in virally infected cells or tumor cells
Use perforin and granzymes
Only lymphocyte member of innate immune system
"#2, get #12, tell him the boss needs to take out α and β"
Activity is enhanced by IL2, IL12, INFα, INFβ
Induced to kill when exposed to a nonspecific activation signal on target cell +/or to an absence of MHCI on target cell surface

14

B cells functions

Make Abs: opsonize bacteria, neutralize viruses (IgG), Activate complement (IgM and IgG), Sensitize mast cells (IgE)
Allergy (Type I hypersensitivity): IgE
Cytotoxic (Type II hypersensitivity): IgG
Immune Complex (Type III hypersensitivity): IgG
Hyperacute and humorally mediated acute and chronic organ rejection

15

T cell functions
Generally
CD4
CD8

Delayed cell mediated hypersensitivity reaction (IV)
Acute and chronic cellular organ rejection
CD4+ cells help B cells make Ab and produce cytokines to activate other cells of the immune system
CD8+ cells kill virus infected cells directly

16

Differentiation of T cells
In Bone Marrow
In Thymus
In Lymph Node

In BM: T cell precursor
In T: expresses TCR, CD4 and CD8 and then will switch to only expressing one of the CDs and a TCR
In LN: CD8+ --> cytotoxic T cells
CD4+: if exposed to IL12 --> Th1
if exposed to IL4 --> Th2

17

Where is there Positive selection in T cell differentiation?

In the Thymic Cortex where T cells expressing TCR capable of binding self MHC survive

18

Where is there Negative selection in T cell differentiation?

Medulla where T cells expressing TCR with high affinity for self antigens undergo apoptosis

19

APCs
# of signals needed for what?

Dendritic cell (Only APC that can activate naive T cell)
Macrophage
B cell
2 signals needed for T cell activation, B cell activation, and class switching

20

Steps of naive T cell activation

1. Foreign body is phagocytosed by dendritic cell
2. Foreign antigen presented on MHCII
3. MHCII + antigen recognized by TCR on Th cell or MHCI + antigen recognized by TCR on Tc cell
4. Costimulatory signal given by interaction of B7 (DC) and CD28 (T cell)
5. T cell activated: Th produced cytokines, Tc kills virus infected cells

21

Steps of B cell activation and class switching

1. Th cell activated
2. B cell receptor mediated endocytosis
3. Foreign antigen presented on MHCII
4. MHCII + antigen recognized by TCR on Th cell
5. CD40 receptor on B cell binds CD40 ligand on Th cell
6. Th cell secretes cytokines that determine Ig class switching of B cell
7. B cell activates and undergoes class switching, affinity maturation, and Ab production

22

Th1
What do they secrete
What do they activate
What inhibits them

Secretes INFγ
Activates Macs
Inhibited by IL4 and IL10 from Th2

23

Macrophage-Lymphocyte interaction

Activated lymphocyte --> INFγ --> Macs --> IL1 and TNFα --> lymphocytes

24

Th2
What do they secrete
What do they activate
What inhibits them

Secrete IL4, IL5, IL10, IL13
Recruit eosinophils for parasite defense, promote IgE production by B cells
Inhibited by INFγ from Th1

25

Lymph Node
What is it?
Afferents?
Efferents?
Encapsulated?
Function

Secondary Lymphoid Organ
Many afferents
1 or more efferents
Encapsulated w/ trabeculae
Filtration by Macs, storage, activation of B and T cells, Ab production

26

Lymph Node Follicle
Location
Function
Primary vs Secondary

Outer cortex
B cell localization and proliferation
Primary: dense and dormant
Secondary: pale central germinal centers and are active

27

Lymph Node Medulla
What does it consist of?

Medullary cords: closely packed lymphocytes and plasma cells
Medullary sinuses: Communicate with efferent lymphatics and contain reticular cells and Macs

28

Paracortex
Location
What does it house?
What does it contain?
What happens in an extreme cellular response?
Disease?

Between follicles and medulla
T cells
High endothelial venules through which T and B cells enter from blood
In extreme celular response, becomes enlarged
Not well developed in DiGeorge Syndrome

29

Lymph Drainage of Upper limb and lateral breast

Axillary

30

Lymph Drainage of Stomach

Celiac