T and B Lymphocytes Flashcards
What are the names if the two Helper Cells that T cells Express?
CD4 + T Helper Cells
CD8 + T Helper Cells
What is the function of the CD8 + T Helper Cells?
- KILLER cell
- cells kill infected cell by secreting cytokines or inducing apoptosis.
What is the function of the CD4 + T Helper Cells?
- Use T Cell antigens receptors to recognise peptides (opsins)
- Bind to MHC, migrate to T cell zone of lymph node and activate T Cell if matches
- Produce growth factors to enhance growth and T cell division
- Promotes proliferation of CD8 + Helper Cells by release of cytokines
Which type of Immune System uses T and B Lymphocyte to detect pathogens?
-Acquired Immune System
Are B and T Lymphocytes Specific?
- YES VERY!
- only express one specific antigen receptor for the pathogen’s antigen epitope (region on antigen)
What is the name for B cell Receptors?
-B cell Antigen Receptor (BCR)
What is the name for T cell Receptors?
-T cell Antigen Receptor (TCR)
What are Antibodies made of?
-Protein
What is the stricture of a (BCR)?
- Transmembrane protein and binds to one specific antigen
- Made of x4 polypeptide chains (2 heavy and 2 light)
- BCR has a ‘unique variable region’ on antibodies is what makes them specific
What must be combined with the antigen to allow a (TCR) to detect it?
-Antigen must be combined with (MHC)-Protein Complex
What makes T cells Unique?
-Have a ‘Hypervariable Region’
What enzyme breaks down antigens combined with MHC Complex?
-The enzyme ‘Proteases’ breaks down the peptide antigens to short fragments and complex with MHC
How many types of MHC Molecules are there?
-X2 Classes
Describe location and function of Class 1 MHC Molecules.
- On all nucleated human cells
- Have peptide antigens in complex with MHC Molecules
-Describe location and function of Class 2 MHC Molecules.
- ONLY exist on Professional Peptide Antigen Presenting Cells (immune cells)
- Immune cells = Dendritic, macrophages and B Lymphocytes
What is Lymphocyte Migration?
- This is when ‘Mature’ lymphocytes circulate in the blood stream
- Travel to Secondary lymph nodes
What regulates Lymphocyte Migration?
-Regulated by Adhesion and Activation Cascades
How are B cells Activated?
1) Phagocyte degrades pathogen and releases debris (inc antigens) into extracellular space
2) Antigens released travel to the Lymph Nodes and if finds matching B Lymphocyte> Activated.
How are T cells Activated?
1) Phagocyte degrades pathogen and releases debris (inc antigens) into extracellular space
2) Antigen MUST be communed with MHC Complex for T cell to recognise it
3) Dendritic cell PRRs recognise Antigens and complexes the antigens with MHC Complex
4) 3) Antigen-MHC Complex migrates to lymph node and if in same follicle as matching T cell> activated.
What X2 Signals does B cell require to become fully activated? (AH)
1) Antigen Signal Engagement
2) Helping Signals
What happens once B cells are activated?
- The B cell differentiates into a plasma cell
- Plasma cell produces Antibodies.
What is Hypermutation?
-This is when B intentionally mutates so they can produce better Antibodies.
What Antibodies are formed from Hypermutation?
IgM antibodies undergo Hypermutation to form IgG
What do the X2 Activation Signal for B Lymphocytes produce?
- From short life plasma cells
- Produce low affinity-antibodies
What are Antibodies formed from?
-Plasma Cells
How to Antibodies Eliminate Antigens?
1) Variable region on antibody receptor binds to antigen
2) Effector Function- Inactivates antigens via clearance mechanisms of the heavy chain region of antibody
Name the X5 types of antibodies produced by plasma cells.
- IgG
- IgM
- IgA
- IgD
- IgE
Name the type of antibody produced in a Primary Immune Response.
-IgM
What type of Plasma cells produce IgM and IgG Antibodies?
IgG Antibodies-Short-life plasma cells
IgM-Long-Life Plasma Cells
What is IgM antibody lag period?
-Time taken to produce antibodies
What are the two forms of IgM Antibody?
- Monomeric
- Pentameric
What is the function of the Monomeric form of IgM Protein?
-Mediates B Cell activation
What is the function of the Pentameric form of IgM Protein?
- Activates the Complement System
- Agglutination
What is Agglutination?
- Antibody clumps are formed
- Clumps formed via cross-linkage
- Mediates IgG and IgM antibodies
-Completed by Pentameric form of IgM Antibodies
What is the most common and effective type of Antibody formed?
IgG
*Common-same letter twice gG
What type of plasma cells produce IgG proteins?
-Long-Life Plasma Cells
What are the functions of the IgG Antibodies?
- Opsonisation
- Neutralisation
- Activates Complement System
- NK Cell Activation
What is the Complement System?
-Group of proteins that enhance immune response
What is Neutralisation?
- Completed by IgG Antibodies
- When specific antigen binding to IgG antibody receptor occurs to neutralise toxins
What form does IgG Antibodies take?
-Monomeric
What is common function of antibodies in Monomeric form?
-B Cell Activation
What is the function of IgA antibodies in Monomeric form ?
-Neutralisation
What two forms cam IgA Antibodies take?
- Monomeric
- Dimeric
What is the function of IgA antibodies in Dimeric form ?
- Neonatal defence
- Neutralisation
What can T cells Differentiate into?
-Helper Cells
What happens when a CD4 + Helper Cell is activated?
–If activated CD4 Helper cells differentiate into effector cells- TH1, Th2,tFH and regulatory T Cells.
What type of Helper Cell enhances T cell Proliferation and Growth Factors Production?
-CD4 + Helper Cell
What do CD8 + Helper Cells rely on?
-CD4+ Helper Cells producing Cytokines so CD8+ Cells form
After an Immune Response what happens to the immune cells that have been formed?
- Slowly die off
- BUT some stay as Memory Cells
What happens to Macrophages (Pro-Inflammatory mediators) after there has been an immune response?
-Change from Pro-Inflammatory> Anti-Inflammatory Mediators
