Dendritic cells and Class II MHC/HLA Flashcards

1
Q

In vivo Dendritic cells are derived form

A

CD34+ bone marrow stem cells

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2
Q

In vivo immature dendritic cell differentiation

A

under influence of GM-CSF, M-CSF, Flt3 ligand. Myeloid precursors enter circulation and differentatie to dendritic cells

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3
Q

In vivo maturation of dendritic cells

A

mature after they endocytose an antigen

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4
Q

In Vitro dendritic cell precursors

A

Blood monocytes or CD24+

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5
Q

to differentiate dendritic cells invitro add

A

GM-CSF, Flt3, IL-4

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6
Q

FLt3 receptor is also known as

A

CD135

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7
Q

Role of dendritic cells

A
  • antigen presentation
  • link innate immunity to adaptive immunity (+cytokines)
  • secrete cytokines( IL12,15,18,23)
  • capture antigen and transport to secondary lymphoid tissue to present to CD4+(immature)
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8
Q

Distribution of dendritic cells

A

all lymphoid and non lymphoid tissue except brain

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9
Q

Phenotype for dendritic cell and other APCs for antigen presentation

A

HLA-Class II, B7-1/CD80, B7-2/CD86

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10
Q

other cell surface molecules of dendritic cells

A

Fc-gamma-R, CD-40, LFA-3, ICAM1, ICAM2

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11
Q

Structure of Class II MHC

A

Heterodimer, isoypes DP, DQ, DR. Binds antigenic fragments of 15-30 amino acids long

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12
Q

properties of Class II MHC

A
  • only expresed on APC’s
  • normally express all three isotypes
  • polymorphic in population
  • codominant expresion= six stable heterodimers
  • IFN-gamma upregulates expression
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13
Q

Nomenclature for HLA class II molecules

A

Class II MHC- major histocompatibility complex-any species

HLA-Class II- Human leukocyte antigen

H-2 mouse(histocompatibility-2 mouse IH2-IA, H2-IE

Human Class Region- HLA-DP, DQ, DR

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14
Q

dendricit cell antigen processing

A

endocytose into endosome and fuse with lysosome.

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15
Q

HLA class II molecules and innvariant chain are assmbled in

A

ER

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16
Q

complex HLA-class II=

A

trimeric, invariant chian blocks heterdimer antigen binding site

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17
Q

HLA class II is transported

A

in vesicles toward membrane

18
Q

en route to membrane, HLA vesicles

A

fuse with endosome-lysosome vesicle and form chimeric vesicle

19
Q

lysosomal enzymes degrade

A

invariant chain (Li)

20
Q

antigen peptides bind to

A

groove in heterodimer

21
Q

after antigen binds to chimeric vesicle it is

A

transported to and fused with membrane

22
Q

both antigen and peptide complex on dendritic cells are

A

displayed on the cell surface.

23
Q

activation interactions of dendritic and CD4+

A

HLA- class II peptide w/ t Cell antigen receptor -HLA class II receptor w/ CD4 -B7-1/CD80 w/ CD28(costimulatory) -B7-2/CD86 w/ CD28(costimulatory) - LFA-3 w/CD2 (adhesion - ICAM-1 w/ LFA-1(adhesion) - ICAM-2 w/LFA-1 (adhesion) - CD40 w/ CD40L (CD154) (enhances T cell response)

24
Q

down regulation of ineraction of Dendritic cell with Tcell

A

B7-1/CD80 and B7-2/CD86 with CTLA4/CD152 causes inhibtion of T-cell

25
Q

Cross presentation

A

process by which exogenous antigens(normally are processed in phagolysosomes) are presented on APC cell surface

26
Q

only cell to mediate cross presentation for the most part

A

dendritic cells

27
Q

following cross presentation exogenous antigens can be presented

A

within the context of Class I MHC, to CD8+

28
Q

Antigen presenting cells

A

dendritic cells, macrophages(only CD4+ in primary response ), b-cells(Only to CD4+ in primary response) which all express FcgammaR

29
Q

neutorphils and NK cells express

A

FcGamma R but are not APC

30
Q

IN Vitro FLT3/CD135 regulates

A

differentiation, growth and survival of CD34+ progenitor cells.

31
Q

dendritic receptors for chemokines direct them

A

to the secondary lymphoid tissue after they encounter an antigen

32
Q

dendrites secrete cytokines when

A

they present to t- cells in the immune response site.

33
Q

antigen presentation delivers the first

A

signal in T cell activation

34
Q

MHC genes are located on

A

chromosome 6

35
Q

Class II MHC restriction

A

CD4+ molecules only recognize antigenic peptides ifthey are displayed with Class II MHC molecules.

36
Q

after association with class II MHC CD4+ cells

A

are further activated to secrete cytokines in the presence of costimulatory signals

37
Q

when microbes thrive extracellularly some are

A

endocytosed by APCs

38
Q

CD4

A

expressed by dendrite cells, determines T-cell lineage and function. is a receptor for HIV type 1

39
Q

HIV-1 infection is initiated by

A

interaction of viral envelope proteins with CD4 and either CCr5/CXCR4

40
Q

immature dendritic cells express both

A

CD4 and chemokine receptors.

41
Q

people with defective CCR5 can be resistant to

A

infection with HIV-1