Immuno 1: Immune Response To Infection/primary Immune Deficiencies 1 Flashcards
List 4 ways in which the skin is able to act as a barrier to infection ?
tightly packed keratinised cells
Low PH
Low oxygen tension
Sebaceous glands- hydrophobic oils, lysosymes, ammonia, defensins
List 4 ways in which the mucous membrane acts as a barrier to infection ?
Secretory IgA in the mucous- prevents bacteria from attaching and penetrating
Lysosymes
Lactoferrin- starves bacteria of iron
Cilia- actively traps and removes bacteria
Which receptors allow cells of the innate immune system to recognise pathogens ?
PRRs - pattern recognition receptors
List 3 polymorphonuclear cells ?
Neutrophils
Eosinophils
Basophils
How do Neutrophils detect immune complexes ?
They have Fc receptors for the Immunoglobulin (antibody) in the complex
Give one example of how neutrophils and Macrophages differ in function ?
Macrophages can also phagocytose pathogens but they are able to process the antigen and present the antigen to T cells
Give 2 examples of PPRs ?
Toll like receptors
Mannose receptors
Give 3 examples of opsonins ?
Antibodies
Complement
Acute phase proteins - CRP
Give 2 examples of enzymes involved in oxidative killing of pathogens ?
NADPH oxidase - converts oxygen into reactive oxygen species
Myeloperoxidase- catalysts the production of HCL acid
Give 2 examples of enzymes involved in non-oxidative killing of pathogens ?
Lactoferrin
Lysozyme
What is pus ?
Collection of dead and dying neutrophils in infected tissues
Which inhibitory receptors stop NK cells from destroying self cells ?
HLA receptors
Which activating receptor causes NK cells to become cytotoxic ?
Heparan sulphate receptors
Which chemokine receptor mediates the migration of dendritic cells into the lymphatics to lymph nodes ?
CCR7
What is the role of Dendritic cells ?
They reside in peripheral tissue and can phagocytose pathogens.
They then migrate into the lymphatics and present the processed antigen to T cells to prime the Adaptive immune system.
Where does lymph re enter the circulation ?
Thoracic duct
How do NK cells recognise infected cells ?
The infected cell (e.g dendritic cell )will down-regulate inhibitory molecules such as HLA and up-regulate activatory molecules such as modified pathogen antigen.
The NK cell can now recognise the cell as altered cell and starts cytotoxic killing
List 2 organs that are considered primary lymphoid organs ?
Bone marrow
Thymus
Where does T cell maturation occur ?
Thymus
Where do B cells undergo affinity maturation and isotope switching ?
Germinal centres
Give 3 examples of secondary lymphoid organs ?
Lymph nodes
Spleen
MALT- mucosal associated lymphoid tissue
What does the TCR do ?
Recognises peptide presented by the target or antigen presenting cell (APC)
Which T cells recognise peptide presented by HLA Class 1 ?
CD8+ T cells
Which T cells recognise peptide presented by HLA Class 2 ?
CD4+ T cells
Which T cells are thought to be associated with Autoimmune disease ?
Th17 T cells
Give 2 ways in which CD8+ T cells cause cytotoxic killing of cells infected by intracellular pathogens e.g viruses
Perforin (forms a pore into cell ) and granzyme
Express Fas Ligands
Which T cells express Foxp3 and CD25 ?
T reg cells
Which T cell helps in B cell maturation ?
Tfh cells (follicular helper)
What is somatic hypermutation ?
The variable region of the B cell antibodies / receptor are edited
What are the 3 pathways of complement activation ?
Classical
Alternative
MBL- mannose binding leptin
How is the classical complement pathway activated ?
Immune complexes
How is the MBL complement pathway activated ?
MBL binds to a microbial carbohydrate such as mannose
How is the alternative complement pathway activated ?
Bacterial cell walls components bind directly to C3z
What triggers the formation of the MAC (membrane attack complex) ?
activation of C3 convertase (common pathway of all 3 complement pathways)
