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Immunology > T and NK Cells > Flashcards

T and NK Cells Flashcards

1
Q

Vocab: Antigens

2 kinds

A

Antibody antigens: all 3D biological molecules

T cell antigens: mostly linear peptides in the context of an MHC molecule

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2
Q

Vocab: Naive Lymphocyte

A

T or B cell that has not encountered specific antigen and proliferated

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3
Q

Vocab: Memory Lymphocyte

A

T or B cell that has recognized/encountered it’s antigen and proliferated

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4
Q

Primary Lymphoid System

A

Thymus and bone marrow where lymphs develop

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5
Q

Secondary Lymphoid System

A

Lymph nodes, where the lymphs hang out looking for trouble

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6
Q

Spleen

A

Second largest lymphoid organ, filters anitgens in blood stream
Red pulp: destroy old RBCs
White pulp: contain lymphoid tissue

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6
Q

B and T Cell Functions

B, Th, CTL, Treg, NK

A

B: neutralize microbe, phagocytosis
Th: activation of macrophage, inflammation, activation of T and B
CTL: killing infected cell
Treg: suppression of immune
NK: killing of infected cell

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6
Q

Goal of Immune Repertoire

A

Large enough to recognize any pathogen, specific enough to not harm the self

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7
Q

T Cells and Differentiation

Types and markers, TCR info

A

All T cells: CD3
T cell receptor (TCR) complex: recognizes specific peptide antigen in the context of an MHC molecule, all have CD3
Helper T: CD4+
Cytotoxic T: CD8+

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8
Q

TCR Chains and Formation

A

Alpha: V+J+C
Beta: V+D+J+C
Rearranged DNA from germline DNA

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9
Q

Where Do Naive T Cells Develop?

A

Thymus

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10
Q

T Cell Selection Process

positive and negative

A
  1. All thymocytes express CD4+8
  2. Positive selection: exposed to MHC molecules. If it engages with MHC Class I, then turns into CD8. If engages with MHC Class II, turns into CD4. If no engagement, apoptosis
  3. Negative slection: MHC with self peptide, if reacts to it then apoptosis, if not then it lives

Less than 5% of thymocytes leave thymus as naive T cells

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11
Q

Two Main Types of T Cells

And their functions

A
  • CD4: helper, 2/3 of peripheral t cells, recognize antigen and MHC II proteins, produce cytokines to help direct immune response
  • CD8: cytotixic, 1/3 of t cells, recognize antigen and **MHC I **proteins, kill virally infected cells
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12
Q

What Induces T Cell Proliferation?

A

IL-2

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13
Q

T Cell: Co Stimulation

A

Requires: activated APC
- APC increased expression of costimulators and secretion of cytokines

If APC is inactivated, T cell has no response

Lack of co stimulation: T cell does not fully activate, causes anergy

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14
Q

Types of T Cell Connections

Importance of CD28

A

Anergy/tolerance: MHC and TCR bind with CD8/4, but CD28 doesn’t bind

Nothing happens: self cell with CD28

Activation/expansion: APC with MHC binds to TCR, CD28 binds to self cell marker, CD4/8 also bound

Inactivation/suppression: CTLA-4 bound to self cell, MHC, TCR, 4/8 all bound

15
Q

How CD8 T Cells Kill: Cytotoxic

A

MHC I peptide, costimulatory molecules, cytotoxic T cell activated

Perforin: makes a pore in the cell
Granzyme: passes through pore and induces apoptosis

Also fas/fas ligand which also causes apoptosis

16
Q

Types of Th Cells

3 of them

A

Th1: makes interferon gamma IFN-y, and tumor necrosis factor-beta TNF-b, protects against intracellular pathogens

Th2: produces interleukins, helps B cells produce antibodies against extracellular pathogens

Treg: CD4 and CD25, suppress immune response by making transforming growth factor B and IL-10, expresses CD25 and CTLA-4

17
Q

Difference Between Effector and Memory T Cells

And why?

A

Long process to prepare naive cell, but lots of energy consumed to keep the matura T cells activated

Memory cells: just remembers past infection, lower activation threshold, lasts a long time

Effector cells: activated and ready to respond

18
Q

Natural Killer Cells: Function

A

Kills target cells without prior exposure

  • Produces IFN-y
  • Involved in early infection
  • FasL and perforin granzyme methods of killing
19
Q

Natural Killer Cells: Stimulation and Inhibition

A

Stimulation: exposure to IL-12, IFN-y, and IFN-b, antibody-coated cells through antibody-dependent cell cytotoxicity (ADCC)
Inhibition: recognizing MHC I, doesn’t attack healthy self cells

20
Q

Natural Killer Cells: Importance of MHC Proteins

A
  • In diseased cells, lose the ability to make MHC
  • NK cells triggered by the lack of MHC
21
Q

Natural Killer Cells: Preventing the Killing

And virus process?

A

Inhibitory receptor: KIR

Viruses: down regulate MHC I on host cell to hide from phagocytes and T cells, but NK is stimulated by lack of MHC so it ends up attacking it

Immunology (14 decks)

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