Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Immunology > Assignment 3 > Flashcards

Assignment 3 Flashcards

1
Q

what is the role of antigen presenting cells?

A

they deliver antigen to CD4+ T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name 3 antigen presenting cells?

A

dendritic cells
macrophages
B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

explain the term antigen presentation

A

the process when antigen presenting cells deliver antigen to CD4+ T cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the major histocompatibility complex (MHC)?

A

encodes proteins that define antigen presenting molecules

a gene complex originally identified because of its role in graft rejection

The major histocompatibility complex (MHC) is a set of cell surface molecules encoded by a large gene family in all vertebrates. MHC molecules mediate interactions of leukocytes, also called white blood cells (WBCs), which are immune cells, with other leukocytes or body cells. MHC determines compatibility of donors for organ transplant as well as one’s susceptibility to an autoimmune disease via crossreacting immunization. In humans, MHC is also called human leukocyte antigen (HLA).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what do all antigen presenting cells express and require for T cell stimulatory function?

A
  • cell surface class II MHC

- costimulatory molecules (CD80 and CD 86 and CD 40).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are CD8+ T cells? Why?

A

not antigen presenting cells, they are target cells

the antigen displayed in their cell surface (with class I MHC) targets them for CD8+ T cell mediated death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

why are all nucleated cells a potential target cell?

A

all nucleated cells express class I MHC - potentially be destroyed!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where are immature dendritic cells present?

A

in all lymphoid and non lymphoid tissue except the brain - including mucosal epithelium of the oral cavity, anus and vagina

skin = aka Langerhans cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the function of dendritic cells?

A

sentinel cells (or gatekeepers) in peripheral tissues where they capture antigens and carry them to secondary lymphoid tissues (to the T cells)

some are also resident in secondary lymphoid tissue where they capture antigens that have invaded that site!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

phenotypically, what do immature dendritic cells express high concentrations of?

A

FcϒR

also express CD 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

phenotypically, what do immature dendritic cells express low concentrations of?

A
  • class II MHC

- co stimulatory molecules (B7-1, B7-2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is CD4?

A

one receptor for HIV, type 1 (HIV-1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

infection with HIV-1 is initiated by interaction of

A

viral envelope proteins with (at least) 2 receptors

  • CD 4
  • chemokine receptor = CCR5 and/or CXCR4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

why can dendritic cells be targets for HIV infection?

A

because they express CD 4
HIV-1 uses CD4 to gain entry into host T-cells and achieves this by binding to the viral envelope protein
HIV infection leads to a progressive reduction in the number of T cells expressing CD4.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

why are macrophages not particularly effective as antigen presenting cells during a primary immune response?

A

macrophages cannot capture antigen in the periphery and transport it to the appropriate lymphoid tissue - dendritic cells can.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

where do primary immune responses occur

A

in secondary lymphoid tissues (where T cells hang out)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

where do secondary immune responses occur?

A

site of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

why are B cells able to function as well as an antigen presenting cell in secondary immune responses?

A
  • use antigen specific receptors (membrane antibody)
  • the receptors are so specific that B cells can bind antigen even when the antigen is in low concentration
  • binding of B cell and antigen is followed by internalization of the receptor and the antigen into an endosomal vesicle = processing is the same as in APCs
19
Q

what is the difference between the terms HLA, H2 and MHC?

A

MHC proteins - class I and class 2 (generalized)
Humans have HLA (human leukocyte antigen)
Mouse has H-2 system (murine system)

20
Q

list the names of the class II MHC molecules in the human

A

HLA-DP
HLA-DQ
HLA-DR

21
Q

list the names of the class II MHC molecules in the mouse

A

murine –
H2-IA
H2-IE

22
Q

what are the major structural features of class II MHC

A

dimer alpha chain binds (restricted to binding proteins 15-30 aa)

23
Q

what is the role of class II MHC?

A

they present the antigen to CD4+ T cells

recognized by CD4+ T cells

24
Q

what is class II MHC restricted?

A

CD4+ T cells are RESTRICTED to “see” antigen only in associated with class II MHC

25
Q

what is the role of the invariant chain?

A

prevents binding of endogenous peptides to class II MHC receptor in ER

26
Q

what is MHC polymorphism?

A

the distinguishing characteristics of class I and class II MHC molecules

polymorphic (more than one type) in population = survival advantage!

27
Q

what are the molecular interactions of APC — T cell?

A 
APC------TCell
class II MHC peptide ---TCR
Class II MHC ---- CD4
CD80/CD86 (*costim) ---CD28
LFA-3 (*adh)----CD2
ICAM (1,2,3)(*Adh) --LFA-1
CD40---CD40L (CD 154)

LFA - lymphocyte function associated antigen
ICAM - intercellular adhesion molecule

28
Q

list the names of the class I MHC molecules in the human

A

HLA-A
HLA-B
HLA-C

29
Q

list the names of the class I MHC molecules in the mouse

A

H2-K
H2-D
H2-L

30
Q

what is the minimum number of different class II and class I MHC molecules in unrelated parents?

A

minimum of 6 different class II molecules

31
Q

where are class I MHC present?

A

on all nucleated cells

32
Q

what are the major structural features of class I MHC?

A
  • heavy chain (trnasmembrane polymorphic polypeptide)
  • Beta2-microglobulin (smaller polypeptide)

*non covalently bound together

33
Q

what is the function of B2 macroglobulin

A

class I MHC 45 kd chain does not fold properly when its not around?

non-polymorphic
no transmembrane domain
encoded on chromosome 15
does not bind antigen fragments

34
Q

what is the role of class I MHC?

A

infected cells express class I MHC –> destruction by CD8+ Tcell

35
Q

define class I MHC restricted?

A

CD8+ Tcells are restricted to seeing antigen in association with class I MHC (antigen/MHC class I complex)

36
Q

what is cross presentation?

A

process by which exogenous antigens normally processed in phagolysosomes and presented on the cell surface are instead presented by class I MHC molecules

37
Q

what cells primarily mediates cross presentation?

A

dendritic cells

38
Q

what is cross priming?

A

class I MHC present antigens to CD8+ T cells - activation of CD8+ Tcells

39
Q

define determinant selection

A

a phenomenon in which the MHC molecules present on the cell do not bind a particular peptide and so that peptide cannot be presented to T cells

Nonresponsiveness: peptide can’t be presented to T cells so no immune
response generated against it

40
Q

explain the phrase “hole in the repertoire”

A

states that and individual may not have T cells with receptors that can recognize particular peptide-MHC complexes. This is entirely likely due to the phenomenon of negative selection which occurs during thymic education.

41
Q

how does the role of CD1 molecules differ from that of Class I and class II MHc?

A

CD1 - similar to MHC class 1 –> form complex with Beta2 macroglobulin

CD-1 antigen complex - similar to MHC class II –> processing and cell surface presentation

42
Q

Class I MHCs bind peptides only from ____sources

A

ENDOGENOUS

43
Q

identify the steps of antigen processing that are negatively affected by various herpes viruses - HSV

A 
neurons express small amount of class I MHC = safe haven for virus
HSV produces immediate early protein hat binds to cytosolic portion of TAP transporter-> inhibits transport of peptides from cytosol to ER
with no trnasport to ER -- MHC class I/peptide complexes don't form! - virus is undetected by body!
44
Q

identify the steps of antigen processing that are negatively affected by various herpes viruses - EBV

A

inhibits the activity of proteosome - virus prevents hydrolysis of viral proteins into peptide size fragments
MHC/peptide complex won’t bind in groove maybe because they are too big - EBV stays sequestered in B cell

Immunology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions