Flashcards in Immunology Deck (85):
What do mycobacteria infect?
They infect antigen presenting cells
Where are the blood tissue barriers and hence immune privileged tissues?
What are warm antibodies?
What are cold antibodies?
Which antibodies form monomers?
Which antibodies form dimers?
Which antibodies form pentamers?
Which antibodies cannot cross the placenta?
Give examples of uses of passive immunity
Pooled Ig for immune deficiencies
To prevent rhesus disease
What is caused by the measles vaccine?
What is the marker for memory b cells?
What is the marker for memory T cells?
What are the 6 types of vaccine?
Killed whole pathogen
What is an attenuated pathogen?
Made unable to grow in the human body or grow slowly
What is the function of adjuvants?
Increase the immune response
What adjuvant is used in viral vaccines?
How does HIV enter T cells?
Gp120 on HIV binds CD4
What are the problems associated with a HIV infection?
Antibodies against gp120 can enhance infection in macrophages
Initial infection is transmitted by infected cell not by free virus
What are 5 types of immunodeficiencies?
X linked agammablobulinemia
T cell deficiency
What are treatments for immunodeficiencies?
PEGAylated ADA injections
Pooled gamma globulin
What mutation is associated with x linked agammaglobulinemia?
Btk which causes mutational arrest of B cells
What are 3 contributory causes of MS?
What gene is associated with MS?
What are the antigens in MS?
What is the pathophysiology of MS?
CD4 T cells are activated by APC, they express VLA4 so can cross the blood brain barrier. T cells cause inflammation with leads to demyelination. Increased levels of IgG and leukocytes are found in the cerebrospinal fluid
How does a decrease in vitamin D cause MS?
Increases inflammation. Less vitamin D = more Th1 response
What treatments are available for MS?
Interferon beta (inhibits IFN gamma)
Antibody therapies (rituximab against b cells and natalizumab against VLA4)
Cyclophosphamide (promotes Th2 response and is toxic to proliferating cells)
What does the classical complement system recognise?
What does the MBP/lectin system recognise?
What does the alternative pathway recognise?
What is the result of all 3 pathways?
Production of C5 convertase and MAC
Why does complement have to be regulated?
To prevent it attacking host membranes
What regulates complement?
C3 convertase disrupters
C3 + C3 convertase = C5 convertase
C5 convertase is cleaved to form C5a and C5b. C5b directs the MAC.
C5b binds C6 and C7 which then binds to the pathogen membrane. C8 binds to the complex and inserts into the membrane. Many molecules of C9 bind to form a pore
What activates phagocytes?
Antigen antibody complexes
Example of stranger signal
Example of danger signal
Uric acid from breakdown of purines in dying cells
How do phagocytes kill bacteria?
Where in a phagocyte are bacteria digested?
Phagosomal lysosomal compartment
What is respiratory burst?
How phagocytes kill bacteria. It consumes oxygen and is initiated by NADPH oxidase
How does the respiratory burst kill bacteria?
Production of ROS
What diseases are associated with phagocytosis?
Chediak higashi syndrome
Leukocyte adhesion deficiency
Chronic granulomatous disease
What is chediak higashi syndrome?
Improper phagosomal lysosomal function
Leukocyte adhesion deficiency
Prevents phagocytes migrating
Describe the structure of an antibody
Two light chains
Two heavy chains
Variable region with 2 antigen binding sites
Constant (Fc) region
What are the types of immunoglobulin in order of abundance?
IgG IgA IgM IgD IgE
Where are IgM and IgG found?
Where is IgA found?
Where is IgD found?
Restricted to the B cell membrane - is a B cell receptor
What is the role of IgE?
Activates mast cells
How is antibody diversity achieved?
How are antibody light chains produced?
Combining V J C gene segments
How are antibody heavy chains produced?
Combining VDJC gene segments (D = diversity)
What controls gene rearrangement in immunoglobulin?
Rag 1 and rag 2 recombinase
What do mutations in RAG genes lead to?
Omenn syndrome (severe immunodeficiency)
How do B cells change the sub-type of antibody?
What is the role of AID
Controls somatic hypermutation in antibody genes. This can increase antibody affinity
Describe MHC I antigen processing
Cytosolic proteins are degraded by the proteasome, transported to ER by tap, trimmed by ER peptidases, loaded onto the binding groove of MHC I which is then trafficked to the cell membrane
What are CD1 molecules?
Bind non-self glycolipids and present them to T cell receptors on NK cells
Describe MHC class II antigen processing
MHC II assembles as heterodimers in the ER. Invariant chain binds to the peptide binding groove. Transported to an endocytic vesicle which is acidified to cleave invariant chain to CLIP. Engulfed pathogen proteins are degraded by the proteasome and bind to the peptide binding groove thanks to HLADM. MHC is then trafficked to the cell surface.
Where are T cells selected?
What are CD4 T cells?
Helper T cells (provide help to B cells)
What are CD8 T cells?
Kill virally infected cells
What are Tregs
T cells which modulate the immune system
What happens when the T cell receptor is stimulated?
The T cell divides to produce clones with the same T cell receptor specificity
T cell receptor genes
VJC for the alpha chain
VDJC for the beta chain
How are T cell receptor genes rearranged?
Rag dependent mechanism
What coreceptor does the T cell receptor require?
What co receptor does the B cell require?
Ig alpha beta heterodimer
Which cytokine stimulates T cell clone expansion?
What is the role of interferon gamma?
Suppresses viral infection of cells
What releases IL1 and TNF alpha
TNF alpha receptor pathway
Signals through MAP kinase or ERK kinase to activate NFkB
Il1 signalling pathway
Signals through MyD88 and IRAK kinase
How do T reg cells maintain peripheral tolerance?
Secrete cytokines that inhibit autoreactive T helper cells
Transplant from recipients own tissues
Transplant from non-identical members of the same species
Transplant from genetically identical individuals (monozygotic twins)
Transplant from different species
Rejection within minutes of transplant
Rejection within 2 weeks of transplant due to MHC mismatch
Months to years after transplant, mechanism unknown
Which immunosuppressant drugs are used in transplants?