Immunology Flashcards
3 patrolling immune cells under the skin surface?
Mast cells, tissue macrophages and dendritic cells
Key feature of a pathogen and innate immune cell that allows antigen detection?
PAMPs and PRRs
4 key events after organism has breached the skin?
- PAMP binds mast cell PRR and causes release of histamine
- Histamine causes increased vascular permeability and vasodilation
- PAMP binds macrophage/dendritic PRR which causes release of cytokines which attract other WBCs
- Dendritic cells present to helper T cells which activate B cells (connects innate to adaptive)
What is the main cell of the innate immune response?
Neutrophil
What cells are involved in the clearance of bacteria and fungi?
Macrophage + neutrophil
Macrophage action of killing + what 3 things are secreted after + secretion role?
- Pulls pathogen into lysosome containing ROS which destroys pathogen
- Macrophage releases TNF alpha, IL-1 and IL-8 which promote inflammation and recruit neutrophils
What attracts neutrophils to infection site + maintenance of neutrophil levels?
- Macrophages release TNF alpha + IL-8
- Neutrophils release TNF alpha to attract more neutrophils (positive feedback)
2 extracellular + 2 intracellular neutrophil killing mechanisms?
- NETs trap pathogens until macrophage can phagocytose + degranulation by releasing toxic chemicals
- Phagocytosis + ROS-dependent killing
Examples of ROS and how they are made?
- NAPDH oxidase + oxygen = OO (superoxide)
- OO + NO = peroxynitrite (ONOO)
How many proteins in the complement system?
30
Where are complement proteins made?
In the liver
What initiates the classical complement pathway?
IgG and IgM binding C1
What initiates the alternative complement pathway?
IgA or gram -ve bacteria
Complement cascade summary?
- Runs in order e.g. C1, C2 etc.
- CRP primes bacteria for destruction via complement response
- C3 produces C3a and C3b
- Can also be cleaved by mannose-binding lectin
- C3b degrades unless bound to a cell surface
- Bound C3b cleaves C5 into C5a and C5b
- C5b-C9 = MAC which punctures cells to cause lysis
Role of C3a and C5a?
Cause release of pro-inflammatory mediators
Name 4 opsonins?
CRP, C3b IgM and IgG
Transendothelial migration summary?
- Vasodilation via histamine allows WBCs to move to margins of vessels
- Increased expression of selectins (ICAM and VCAM) via TNF-alpha and IL-1 binds to integrins on WBC
- Interaction is initially weak so rolling occurs but then affinity increases
- WBCs move out of vessel via diapedesis helped by VEGF
- Chemotaxis of WBC to site of injury
What acute cell controls virally infected or cancer cells?
NK cells
How NK cells detect viral/cancer cells + killing action + what is secreted after + 2 effects of secretion?
- Infected cell releases IFN alpha/beta which activates NK cells
- NK cells use perforin to puncture cell
- NK cells produce IFN gamma which increases macrophage ROS production and general expression of MHC II
What controls worm infections?
Mast cells
What 2 ways do mast cells clear parasites?
Degranulation or increasing gene expression for pro-inflammatory mediators
Primary and secondary lymph tissue?
Primary = bone marrow and thymus/ secondary = tonsils and spleen
Site of B cell maturation?
Bone marrow
Site of T cells maturation?
Thymus
Igs on a naive B cell?
IgM and IgD
How B cells reach GC + activation + effect of activation?
- Enter lymph nodes via HEVs
- Activated by T cell + antigen in GC
- B cells changes to plasma cell and makes higher affinity IgG/A/E
Membrane bound Igs?
IgM and IgD
Soluble Igs?
IgG, IgA and IgE
Antibody structure?
- Y shape with outer lighter chain and inner heavy chain
- Hinge region held by disulphide bond
- Fc region at the stalk and variable region at ends of both branches
Order of Ig abundancy?
GAMDE
3 roles of IgG?
Immune complex formation, foetal protetion, complement activation
3 roles of IgA?
Mucus membrane protection, most produced Ig and activates alternative complement cascade
4 roles of IgM?
Pentamer when secreted, immune complex formation, complement system activation, first Ig produced in infection
Role of IgD?
Activates B cell
3 roles of IgE?
Protects against helminthes/protozoa, mediates allergic responses, triggers histamine release
2 things needed for T cell activation + requirement?
- MHC complex + APC co-stimulatory molecule
- Only accept peptides presented by MHC class I or II
Cells with MHC class I and what they present to?
All nucleated cells and CD8+ T cells
Cells with MHC class II and what they present to?
APCs and CD4+ T cells
What cells do CD4+ T cells activate?
CD8 + T cells, macrophages and B cells
Role of TH0?
Releases IL-2 to cause CD4+/CD8+ T proliferation
Role of TH1?
Releases IFN gamma to increase macrophage ROS production
Role of TFH?
Stimulates GC reaction which causes B cells to become plasma cells and undergo Ig class-switching
Function of CD8+ T cells + 2 ways they kill?
Kill viral/cancer cells via Fas or perforin protein
Special dendritic cell feature+ how they link innate and acquired immunity?
- Expresses MHC class I and II
- MHC + APC co-stimulatory molecule activates T cells
- T cells activate B cells
Causes of the features of inflammation?
Rubor and calor = vascular permeability, tumor = loss of water via increased permeability, dolor = fluid pushing on nerve ending and loss of function
What regions of a T cell TCR binds MHC?
Alpha and beta
What key IL inhibits inflammation?
IL-10
What molecule increases APC co-stimulatory molecule expression?
TNF-alpha
What cells have IgE receptors?
Mast cells and basophils
Do neutrophils or macrophages live longer?
Macrophages
How is NF-kB activated + 2 roles?
T or B cell activation + T cells maturation and cytokine production
IL that recruits neutrophils?
IL-8
IL that promotes CD4+ and CD8+ T cell proliferation?
IL-2
2 things that activate T cell vs B cell?
MHC/antigen complex + APC co-stimulation signal vs helper T cell signal + antigen
What forms the MAC?
C5b-C9
What complement protein is measured in suspected infection?
CRP
Function of TREG cells + disease associated with mutation?
Inactivates T cells + IPEX syndrome
IL that stimulates IgE production and Fce receptor expression?
IL-13
IL that stimulates eosinophil production?
IL-5
IL that stimulates TH1 and inhibits TH2 cells?
IL-12
IL that activates B cells to produce IgE?
IL-4
Role of cytokine vs chemokine?
Modulate cell behaviour vs allow chemotaxis/ guide WBCs to area of infection
