5 - Adaptive Immune Response Flashcards
What do naive t cells need to become activated and produce an immune response?
Antigen Presenting Cell
Where are antigen presenting cells found in the body?
- MALT
- Lymphoid organs (nodes and spleen)
- Blood circulation (plasmacytoid and myeloid DC’S)
How do antigen-presenting cells capture pathogens?
- Macropinocytosis (soluble molecules like toxins)
- Phagocytosis
What PRR’s recognise gram positive bacteria?
TLR2 - Peptidoglycan, LAM
TLR1 - LPS bacteria
e.g Staph aureus and step pneumoniae
What PRR’s recognise gram negative bacteria?
TLR4 - LPS
TLR5 - flagellin
e.g e.coli and N.meningitidis
What are mycobacteria recognised by on PRR?
TLR4
How do APC’s recognise viruses as they invade the cell so won’t reach a PRR?
PRR on the inside of the cell, e.g TLR3, TLR8 (norovirus), TLR9 (adenovirus)
What are different types of dendritic cells and where are they located?
What is the difference between IgG and IgM?
IgM is the first antibody to be produced when an infection occurs for the first time. IgG confers immunity.
What are the two classes of MHC’s? (Major Histocompatability Complex)
MHC Class I
- HLA-A,B or C
- On all nucleated cells
MHC Class II
- HLA-DR, DQ and DP
- Expressed on macrophages, B cells and dendritic cells
What are the two main features of MHC’s?
- Codominant expression from mother and father to increase number of MHC molecules
- Polymorphic genes to increas the number of antigens presented
Why may people be more susceptible to a particular infection than others?
Everyone has the ability to present but the way they present is different. The thing that is presented will determine how effective the immune response is
What are the two functions of antigen presenting cells?
- Processing of pathogen (e.g endo/exogenous)
- Presentation of microbial peptides
What is the endogenous pathway?
- Processing of intracellular microbes e.g virus
What is the exogenous pathway of processing microbes?
- Extracellular microbes e.g bacteria
What is the structure of MHC class I and II?
What are the two different immunities activated by APC’s and why do they activate different immunities?
Humoral Immunity - Extracellular microbes, MHC class II so get antibodies, complement and phagocytosis
Cell-Dependent Immunity - Intracellular microbes, MHC Class I so cytotoxic T-cells, antibodies and macrophages
What is the importance of everyone having a different set of MHC’s?
Human race not wiped out by a single disease
Why may a patient be HIV positive but still have a high CD4 count?
They may be a LTNP/elite controller. The MHC’s the patient has are ones that the virus needs to replicate so doesn’t destroy them
What clinical issues can the different MHC sets in two different people cause?
- Organ transplant rejection: make sure donor matches MHC of patient
- GvH disease: bone marrow transplant
- Autoimmune disease: e.g HLA-B27 in 90% ankylosing spondylitis patients
Where does adenovirus infect and what does it cause?
Epithelial cells and causes respiratory disease and conjuctivitis
What is the process of destruction if a bacteria gets into the blood stream?
- Macrophages (plasmacytoid and myeloid DC’s)
- Spleen clears
What bacteria would you normally find in the peritoneal cavity?
NONE!! if it gets in it can cause peritonitis
Only contains antibodies, leukocytes, water and electrolytes
What does a perforated bowel look like on x-ray?
Space below the diaphragm and maybe some inflammation as commensals from bowel have leaked out
