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504 - Tissue Bio > Lect 2 > Flashcards

Lect 2 Flashcards

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Biology 101 flashcards
1
Q

In what ways do microbes interact with cells?

A

Can become phagocytosed - or can bind to receptors on cell surface like in epithelial cells

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2
Q

What cells respond to MHC class II molecules and how does the pathway work?

A

On surface of DCs, B cells and macrophages – present antigen to CD4 T cells – peptide from antigen processing in vesicle gets fused with MHC class II molecule in another versicle from ER and the two vesicle fuse together and move to surface of antigen presenting cell on plasma membrane

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3
Q

What cells respond to MHC class I molecules and how does the pathway work?

A

CD8 CTLs respond to MHC class I molecule when proteasome cuts up peptide in cytosol and is brought into ER by TAP (transporter activated protein) where it fuses with MHCI molecule and is brought out in vesicle to surface

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4
Q

Is MHCII and MHCI a peptide or monomer?

A

MHCII is a dimer, MHCI is a monomer

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5
Q

Which chains have the peptide binding region in MHCI and MHCII?

A

MHCI is alpha, MHCII is beta

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6
Q

How long is a peptide recognized by a TCR?

A

8-10 AA with side chains that are able to interact with side chains on MHC molecule

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7
Q

Why are there so many different alleles of MHC molecules?

A

Diversity – allows population to survive viral infections

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8
Q

Where does protein in MHC class I pathway come from?

A

Cytoplasm that is broken down by proteases - marked by ubiquitin (in class I protein is endocytosed)

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9
Q

What cells do not have MHC molecules?

A

Erythrocytes - no nuclei

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10
Q

What is occurring during lag phase of adaptive immunity?

A

Priming to allow cells to proliferate

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11
Q

What happens during priming of T cells?

A

CD28 on a naive T cell and B7 on APC costimulate eachother to activate T cell

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12
Q

What is an anergic T cell?

A

When T cell is non-functional because it did not receive CD28-B7 interaction, still alive but unable to respond only had MHC-TCR antigen interaction

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13
Q

What increases response of macrophages to bacteria through cell-mediated immunity and activvation?

A

Macrophages produce CD40 that is recognized by CD40L (ligand) on CD4 Lymphocyte, CD4 Lymphocyte also produce IFN-y which is recognized by IFN-y receptor on macrophage – leads to activation and allows for killing of phagocytosed bacteria and secretion of other cytokines

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14
Q

How do CTLs kill pathogens?

A

They use perforin to poke holes in membrane that allows entry of granzymes which activate caspases in apoptosis

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15
Q

How do viruses evade CTLs?

A

They down modulate MHC class I molecules by inhibiting antigen presentation by proteins that they produce (such as HSV, CMV, EBV)

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16
Q

What do NK cells do?

A

Contain granzymes and perforin to kill cells in mechanism similar to CTLs but do not need MHC – but recognize activation ligands triggered by DNA damage from stress

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17
Q

What is antibody-dependent cell-mediated cytotoxicity?

A

Uses antibodies that can be recognized by NK cell and be killed – bein gused in cancer immunotherapy

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18
Q

What is CD4 clonal expansion pathway?

A

A naive CD4 T cell is able to become a proliferating T cell that leads to immature effector T cells – subsets develop and TH1 leads to secretion of IFN-y and macrophage activation (phagocytic response) and TH2 leads to secretion of IL-4 and IL-5 leading to B cell activation and antibody secretion (extracellular pathogens)

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19
Q

What is the big difference between CD4 and CD8

A

CD8 is killing and CD4 is cytokine secretion to recruit other cells

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20
Q

What is CD28 dependent?

A

Priming of T cells

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21
Q

What is the normal antigen response b/w an APC and T cell compared to that leading to cell death (leukemia)

A

In normal response IL-2 is released by T cell bound to APC which can bind to cells that cause apoptosis
In cell death, there is either a cease in IL-2 production leading to apoptosis (which can come from PD-L1 binding to PD1 on T cells, or CTLA4 signaling to APC to make IDO to inhibit T cell) or expression of FasL that kind bind to Fas on apoptotic cell

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22
Q

What is antibody excess? and when does it occur?

A

When there is more antibody than antigen – and a B cell with immunoglobulin on surface will interact with antigen which will trigger Fc receptor yIIB to turn off B cell response

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23
Q

What % of B cells become memory cells? and what do memory cells abolish?

A

~5% – get rid of lag period

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24
Q

What is the difference in immunoglobulins and antibodies?

A

Antibodies are soluble immunoglobulins found in body fluids - but immunoglobulins also present as receptors on surface of B-cells – both recognize antigens

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25
Q

What are the components of an immunoglobulin and what holds them together?

A

2 heavy chains and 2 light chains as mirror images of eachother – held together by disulfide bonds

26
Q

Where in serum are antibodies found?

A

Gamma globulin

27
Q

What portion of all proteins in serum are made up of immunoglobulins?

A

1/4

28
Q

What is the function of an antibody molecule is host defense?

A

To recognize and bind antigen and to target the bound antigen to other components of the immune system

29
Q

Which portion of an antibody is responsible for antigen binding and binding to other receptors?

A

Antigen binding occurs on variable region and binding to other receptor occur on constant region

30
Q

What can digest an antibody molecules to lead to 2 antigen binding proteins and one protein to interact with cell receptors?

A

Papain

31
Q

How many domains does the heavy chain have?

A

3 constant - CH1, CH2, CH3

(sometimes CH4) and 1 variable VH

32
Q

How many domains does the light chain have?

A

1 constant CL and 1 variable VL

33
Q

What is the importance of the hinge region of an antibody?

A

It is flexible and allows the antibody to bind molecules that are spaced further apart

34
Q

What are the different isotypes of the constant region of heavy chains of immunoglobulins? and how do they vary?

A

IgG, IgM, IgD, IgA, IgE – different domains and aa make up and carbs bound- (3 in IgG, IgD and IgA and 4 in IgM and IgE)

35
Q

What are the different forms of the constant region of the light chains?

A

Kappa or Lambda – structurally different from eachother – do not play a role in function – any combination with any constant heavy chain

36
Q

Which portion of the antibody plays a role in the function?

A

The constant heavy chains NOT the constant light chains

37
Q

What is the Kappa:Lambda ratio in human Ig?

A

2:1

38
Q

How do the 4 subclasses of IgG vary?

A

From the structure of it’s hinge – give IgG1, IgG2, IgG3, and IgG4

39
Q

What can IgG2 do?

A

Can be superimposed on one another to become covalently linked to form a multimer

40
Q

Which IgG subclass is not divalent?

A

IgG4 – become functionally monovalent in circulation

41
Q

Which Ig exists as a pentamer?

A

IgM

42
Q

Which Ig exists as a dimer in mucosal fluids? and why?

A

IgA – to bind to polyA receptor on epithelial cell to get through and be transported to inside body to bind to pathogens

43
Q

What are the subclasses of IgA?

A

IgA1 and IgA2 – differ structurally from each other in regards to location (IgA2 found largely in colon – large proportion of IgA1 in spleen and nasal mucosa) and type of glycosylation sites

44
Q

Which IgG is found at the highest serum level and which at the lowest?

A

IgG highest and IgE lowest

45
Q

Where is IgE found?

A

Epithelium

46
Q

Where is IgM found?

A

Only in circulation

47
Q

Where is IgA found?

A

On mucosal surfaces

48
Q

Which immunoglobulin gets through placenta to baby?

A

IgG

49
Q

How does the baby receive IgA when it cells are still niave and unable to make it?

A

Through mother’s milk until it can make their own

50
Q

What are the hypervariable regions of the light chain? and what are the framework domains?

A

The hypervariable regions are the loop like structures that come off the beta strands and are important for the ability to bind antigen – the framework domains are the beta strands that are still variable but not as much

51
Q

Which immunogloblins are important in the neutralization of toxins?

A

IgM, IgG, IgA

52
Q

What is opsonization and what immunoglobulins are important for this process?

A

Ability of the antibodies Fc region to bind to receptors on macrophages called FcyRI which increasees internalization of a pathogen – done by all subclasses of IgG and some by IgA

53
Q

Which immunoglobulins are important for sensitization of mast cells (allergies)?

A

IgE

54
Q

Which immunoglobulins are important for sensitization for killing by NK cells?

A

IgG1 and IgG3

55
Q

Which immunoglobulins are important for complement?

A

IgM (best because of pentamer form to poke holes in membrane) also IgG2,3,4 and IgA

56
Q

Which immunoglobulins are important for transport across epithelium and across placenta?

A

Epithelium - IgM and most importantly IgA (dimer going through gut)
Placenta - IgG (protect baby by binding to pathogens)

57
Q

Which immunoglobulins are important for diffusion into extravascular sites?

A

All except IgD

58
Q

Which immunoglobulin is coexpressed on B cells?

A

IgD and IgM

59
Q

Which immunoglobulin is involved in destruction of parasites?

A

IgE

60
Q

What sets of allergic responses by binding to receptors on mast cells?

A

IgE

504 - Tissue Bio (8 decks)

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