Immunology: Initiation of Acquired Immune Responses - T Cells Flashcards Preview

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Flashcards in Immunology: Initiation of Acquired Immune Responses - T Cells Deck (14)
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1
Q

what do T cells recognise

A

peptide antigens expressed on MHC molecules

2
Q

MHC-I molecules are expressed on what type of cell and present to what type of cells

A
  • all nucleated cells

- CD8+ T cells

3
Q

MHC-II molecules are expressed on what type of cell and present to what type of cells

A
  • only antigen-presenting cells

- CD4+ T cells

4
Q

what cells are antigen-presenting

A

dendritic, macrophages, B cells

5
Q

how do dendritic cells present antigens to T cells

A
  • after phagocytosis in inflamed tissues dendritic cells phagocytose debris via PAMPs and PRRs
  • TNF alpha stimulates dendritic cells increasing their expression of co-stimulatory molecules
  • antigen proteins are displayed on MHC-II and the maturing cell drains into lymph nodes
  • here it presents to T cells
6
Q

what 2 signal do T cells need to activate

A
  • peptide from MHC

- second signal from dendritic cell

7
Q

how are T cells differentiated

A
  • a niave CD4+ cell recieves the two signals required allowing for proliferation
  • the now Th0 cell differentiates into effector T cells - Th1, Th2, Tfh or Treg
8
Q

what is the function of Th0 cells

A

secrete IL-2 and differentiate into effector T cells

9
Q

where does T cell differentiation take place

A

lymph nodes

10
Q

what is the function of Th1 cells

A
  • go to sites of inflammation via transendothelial inflammation
  • macrophages reactivate the T cells via MHC-II presented antigens
  • Th1 cell secrete pro-inflammatory cytokines andhacing ROS phagocytosis by macrophages
11
Q

what is the function of Tfh cells

A
  • B cells present antigen via MHC-II
  • T cell moves to B zone and are re-stimulated by B cells
  • it then stimulates B cells to clonally proliferate and differentiate into long lived plasma cells/memory B cells
12
Q

what is the function of CD8+ T cells

A

proliferate and differentiate into cytotoxic T lymphocytes where they enter inflammatory sites and kill virally infected cells

13
Q

how to cytotoxic T cells kill host cells

A
  • cell recognises and binds to virally infected cell (via MHC)
  • T cell programmes for cell death and DNA fragmentation
  • cell migrates to new target and apoptosis occurs
14
Q

how do inflammatory sites return to normal after inflammation

A
  • anti-inflammatory cytokines (IL-10) repairs tissue damage

- T and B cells die leaving memory T and B cells

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