Topic 16 - Cellular immunity, T lymphocytes and the MHC structures of the cells

Question 1

Words to include in cellular immunity

Answer 1

• Antigen idependent phase
  
  • Pre-T-lymphocytes
  • Virgin T-lymphocytes
  • Ig-like molecule (TCR)
  • Ti
  • Initiator cell
  • Primary lymphatic organs (central)
    
    • Haemophilic primordial cells
    • Thymus
    • Cortex
    • Marrow
• Antigen dependent phase
  
  • Ti-cell
  • CD4 cell surface antigen
  • Colony Defining (CD)
  • TCR
  • Antigen
  • APC cell
  • MHC-II antigen
  • AP-cell
  • Interleukin
  • Blastic transformation
  • T-dependent (central) part of the secondary lymphatic organs
  • T-helper cell
  • Circulation
• B-cell activation
• Macrophage activation
• Antigen elimination

Question 2

Words to include in T-lymhocyte

Answer 2

• Thymus
• Bone marrow
• Liver
• Tc-cells
  
  • Virus
  • Bacteria
• Th-cells
  
  • B-lymphocytes
• Treg-cells
  
  • Autoimmune reaction (ø)
  • Immune response
• T-lymphocyte maturation
• T-cell receptor
• MHC structures
• Antigens
• Positive selection
• Negative selection
• Self matters
• Self-MHC molecules
• Antigen elimination
• Phagocytes
• Interleukins
• Pathogenic agent

Question 3

Words to include in MHC

Answer 3

• Major Histocompatibility Complex
• Self
• Non-self
• “Identity card”
• MHC-I
  
  • EC components
  • MHC-gene
  • Transmembrane components
  • IC components
  • Cytotoxic T-lymphocytes
• MHC-II
  
  • Cell surface antigens
  • Antigen presenting cells (APC)
• MHC-III
  
  • Cell surface signals
  • MHC gene group

Question 4

Cellular immunity

Answer 4

1. Antigen idependent phase (1^stt phase)
   
   • Location: Primary lympahtic organs
   • Pre-T-lymphocytes mature and become virgin T-lymphocyte
   • On the surfcace of virgin-T-lymphocyte there will be an Ig-like molecule (TCR) appearing agiant a certain possible antigen structure
   • Ti- cell (Initiator cell) gets into the blood circulation
2. Antigen dependent phase (2^nd phase)
   
   • Location: circulation and secondary lymphatic organs
   • The Ti-cell carries an CD4 cell surface antigen
     
     • This cell can recognize the specific TCR, and an antigen presented by an APC cell, together with an MHC-II antigen
   • Linkage between AP cell and Ti-cell = primary stimulation
   • Interleukin is secreted = Ti-cell is activated and goes through blastic transformation in the T-dependent (central) part of the secondary lymphatic organs

• Result:
  
  • B-cell acitvation
  • Macrophage activation
  • Antigen elimination

Question 5

T-lymphocytes

Location of origin and maturation (steps)

Answer 5

• Origin: Bone marrow and liver
• Maturation: Thymus

​​

• T-lymphocyte maturation:
  
  1. T-cell surface receptors appear
  2. Immature T-cell surface receptor can bind MHC structures and antigens
  3. Positive selection: T-lymphocytes that can bind self-MHC molecules will survive, the rest will die
  4. Negative selection: T-lymphocytes that can bind self matters expressed together with self-MHC molecules will be killed or inactivated

Question 6

T-lymphocytes

What are the T-lymphocytes separated into?

Answer 6

1. Tc-cells
   
   • Cytotoxic T-cells
   • Killing the virus and bacteria infected cells
2. Th-cells
   
   • T-helper cells
   • Helps stimulate the activation of the Tc-cells and the B-lymphocytes needed for the immune response
   • Will cause selective death amongst the Th-cells
3. Treg-cells
   
   • Regulatory T-cells
   • Helps regulate the activation of the Tc-cells and B-lymphocytes needed for the immune response
   • Removal of Treg-cells will result in an autoimmune reaction (?)

Question 7

T-lymphocytes

Antigen elimination

Answer 7

• The T-cell recognises either:
  
  • Only the antigen
  • Both the antigen and the MHC
• It becomes activated and recruits phagocytes with interleukins
• The phagocytes will kill the pathogenic agent

Question 8

MHC

General

Answer 8

• MHC: Mjaor Histocompatibility Complex
• The natural ability to distinguish self from non-self
• Function: The “identity card” of the cells
• Main task: present the (forgein) Ag-related peptides to the T-lymphocytes
• MHC- moleculesare genetically determined cell-surface structure
• They serves as peptide-receptors
• MHC restriction: T-cels can only recognize the Ags together with MHC-molecules
• MHC I and MHC II are immune response related
• MHC III does not play a direct role in the immune response

Question 9

MHC-I

Answer 9

• Composed of:
  
  • EC component encoded by an MHC-gene
  • Transmembrane components
  • IC components

​

• Different antigens of the MHC-I group are recognized by cytotoxic T-lymphocytes, if the cell binds some non-self antigen beside the MHC-I
• Presented on the surface of each nucleated cells

Question 10

MHC-II

Answer 10

• Composed of:
  
  • Cell surface antigens
• Found on antigen-presenting cells (APC)

1. APC send parts of the non-self antigen together with the MHC-II structure onto the cell surface
2. The signal to the helper T-cell is the presence of the MHC-II structure together with the non-self antigen

Question 11

MHC-III

Answer 11

• Cell surface signals encoded by the MHC gene group
• No direct role in the immune response

Question 12

MHC

Figure of MHC-I and MHC-II

Answer 12