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MMD 1229 (Patho) > APP 3 - Système immunitaire adaptatif > Flashcards

APP 3 - Système immunitaire adaptatif Flashcards

1
Q

Quel type de molécule CMH sont exprimé sur TOUTES les cellules nucléées?

A

MHC I

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2
Q

CMH-II est exprimé sur quels types de cellules?

A

Cellules présentatrices d’antigène (CPA)

  • Macrophages
  • Cell. dendritiques
  • B-cells
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3
Q

Helper T-cells (CD4) recognize which type of MHC?

A

MHC-II

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4
Q

Cytotoxic T-cells (CD8) recognize which type of MHC?

A

MHC-I

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5
Q

Which type of T-cells can bind on receptors that are present on all nucleated cells?

A

Cytotoxic T-cells

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6
Q

Which type of T-cells are effective against virus-infected cells?

A

Cytotoxic T-cells

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7
Q

Which type of cells are effective ONLY against extracellular pathogens?

A

Helper T-cells

- Because they bind to MHC-II on CPA

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8
Q

Which type of molecules does MHC-I present?

A

Endogenous peptides (ex: viral antigens)

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9
Q

Do CPA also express MHC-I?

A

Yes!

If infected by a virus, they will bind CD8 t-cells

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10
Q

Combinaison des allèles d’HLA (human leukocyte antigen) chez un individu

A

Haplotype HLA

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11
Q

T or F?

MHC molecules are specific for one peptide

A

False

MHC molecules have a broad specificity for peptide binding

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12
Q

T of F?

Each MHC molecules can only present one peptide at a time

A

True

However, a single cell has many MHC molecules and they can present many different peptides from the same pathogen

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13
Q

Can cells express “empty” MHC molecules (which do not present an antigen) on their surface?

A

Only MHC which present a peptide are expressed in a stable manner on cell surface

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14
Q

CD28 receptor

A

Co-receptor on T-cells

- Bind B7 expressed on APC upon pathogen infection

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15
Q

Role of co-activators (CD28 on T-cells)

A
  • Control T-cell migration into tissues

- Amplify activation signal via Signal 2 (to avoid false positives)

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16
Q

B-cell receptor complex (BRC) are composed of

A
  • IgM

- Signal molecules (Ig-alpha and Ig-beta)

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17
Q

CD21 (also known as CR2)

A

B-cell co-receptor

  • Binds C3d (complement protein fragment) often found on pathogen
  • Induces signal 2 (= activation of B-cell)
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18
Q

How do macrophages participate in the humoral response?

A

They bind to pathogens that are opsonized by

  • Ab
  • Complement proteins

Phagocytoses them
Destroys them

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19
Q

How do macrophages contribute to the adaptive cellular immune response?

A

Reciprocal activation between Helper T-cells and macrophages

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20
Q

2 types of dendritic cells

A
  • Cellules dendritiques interdigitées (conventionnelles)

- Cellules dendritiques folliculaires

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21
Q

Which type of dendritic cells activate T lymphocytes?

A

Cellules dendritiques interdigitées

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22
Q

Which type of dendritic cells activate B lymphocytes?

A

Cellules dendritiques folliculaires

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23
Q

Where are Cellules dendritiques interdigitées located?

A
  • Immature: in epithelium (ex: cellules de Langerhans)

- Mature: dans zones de lymphocytes T (tissus lymphoides)

24
Q

Where are Cellules dendritiques folliculaires located?

A

Rate et ganglions:

dans les centres germinaux des follicules lymphoides

25
Q

Where are T-cells located?

A
  • In circulation

- Rate et ganglions: zones périartériolaire (“pulpe blanche” et interfolliculaire

26
Q

Where are B-cells located?

A
  • In circulation

- Follicule des tissus lymphoides périphériques (ganglions, rate, amygdales, tissus muqueux)

27
Q

Les DC des ganglions lymphatiques captent quel types d’antigènes?

A

Antigènes solubles

Dans la lymphe

28
Q

Les DC dans la rate captent quel types d’antigènes?

A

Antigènes solubles

Dans le sang

29
Q

Rôle du chimiokine CCR7

A

Guider la migration des DC

Épithélium –> Vx lymphatiques –> Ganglions lymphatiques (site de rencontre avec T-cells)

30
Q

Quelles cellules expriment le chimiokine CCR7? (pour attirer DC)

A
  • cellules épithéliales des vx lymphatiques
  • cellules dans la zone des ganglions lymphatiques
  • Lymphocytes T naifs
31
Q

Pourquoi les DC migrent vers la rate, les ganglions, tissus lymphoides?

A

Car plus grande concentration de T-cells à ces endroits = plus grande chance de rencontrer T-cell avec le bon récepteur

32
Q

Les macrophages activent quels lymphocytes?

A

Lymphocytes T

33
Q

Comment les macrophages activent les T-cells?

A

En présentant antigènes sur leurs MHC

et en sécrétant des cytokines (IL-6, IL-12, IL-23)

34
Q

Quel type de protéines sont présentées sur les MHC-I ?

A

Antigènes cytoplasmiques (produits par virus)

35
Q

Naive B-cells produce which type of antibodies?

A
  • IgM+

- IgD+

36
Q

Production of functionally different Ab, all with the same specificity, relies on which process?

A

Heavy-chain class (isotype) switching

37
Q

What does the T-cell receptor (TCR) recognize on APC?

A

Antigen-MHC complex

38
Q

What are CD4 and CD8? (function)

A

Co-receptors on T-cells

- Function as co-activators along with TCR (signal 1)

39
Q

What does CD4 recognize?

A

MHC-II molecules

40
Q

What does CD8 recognize?

A

MHC-I molecules

41
Q

Do CD4 and CD8 play a role as co-stimulators?

A

No. They contribute to activating Signal 1 along with the TCR.

42
Q

Which molecules on CPAs work as co-stimulators?

A

B7 (CD80 and CD86)

their expression is up-regulated upon infection

43
Q

Which receptor do CD80 and CD86 on CPAs bind to?

A

CD28 receptor on T-cells

= signal 2

44
Q

What is the role of adherence molecules on T-cells? (ex: integrines)

A

Stabilize the interaction between T-cell & CPA (to allow sufficient stimulation to occur to activate T-cell)

45
Q

Quel est le rôle du ligand CD40 (CD40L) sur les lymphocytes T?

A

Lier récepteur CD40 sur les CPA

  • Stimulate APC expression of B7 + cytokine production
    = indirectement favoriser la différenciation des T-cells
46
Q

Pourquoi faut-il ajouter un adjuvant dans certains vaccins protéiques?

A

AG protéines: pas toujours suffisants pour déclencher réponses immunitaires dépendantes des T-cells (ce qui est nécessaire pour générer des cellules mémoires)

Adjuvant: induit l’expression de molécules de co-stimulation sur les CPA (ex: B7)

47
Q

What are the 2 primary lymphoid organs?

A
  • Thymus (for T-cell development)

- Bone marrow (for B-cell development)

48
Q

Name some secondary lymphoid organs

A
  • Spleen (rate)

- Lymph nodes (ganglions)

49
Q

T or F:

DC can phagocytose infected cells, and then present antigen peptides from these cells on their MHC-I

A

True! This is especially useful with infected cells that cannot display antigens (ex: RBC)

50
Q

Where do T-cells undergo (+) and (-) selection?

A

In the thymus

51
Q

Negative selection of T-cells

A

If TCR binds to self-antigen presented by MHC-I or MHC-II on thymic cell: T-cell will undergo apoptosis

52
Q

Positive selection of T-cells

A

CD8 and CD4 on T-cells = able to recognize and bind specifically to MHC-I and MHC-II (respectively)

Otherwise: T-cell will undergo apoptosis

53
Q

How does a T-cell become a CD4 or CD8 T-cell?

A

At first, after undergoing both + and - selection in the thymus, T-cells express both CD4 and CD8 co-receptors.

It is by CHANCE that they will interact more strongly with either MHC-I (= up-regulate CD8) or MHC-II (= up-regulate CD4). The other type of MHC will be down-regulated.

54
Q

Role of regulatory T-cells

A

Prevent auto-immune reactions

55
Q

Where are regulatory T-cells found

A

Corpuscule de Hassal (dans thymus)

56
Q

T or F: T-cells are made in the thymus

A

False

They are made in the red bone marrow

MMD 1229 (Patho) (9 decks)

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