Overview Flashcards
What are the cells which are myeloid origin?
- thrombocyte
- erythrocyte
- mast cell
- basophil
- neutrophil
- eosinophil
- monocyte/macrophage
- dendritic cells
What are the cells of lymphoid origin?
- natural killer cells
- T cell
- B cell
What is the function of monocytes?
Circulate the blood then migrate into tissues to differentiate into macrophages
What is the function of macrophages?
- phagocytes
- antigen presenting
What type of macrophage is pro inflammatory?
M1
What type of macrophage is anti inflammatory?
M2
What is the function of mast cells?
- granulocytes
- granules release histamine
- allergy role
What is the function of neutrophils?
- most numerous immune cell
- phagocytes
- granulocytes
- release antimicrobials and degradative enzymes
What is the most numerous immune cell?
Neutrophil
What is the function of basophils?
- granulocytes
- release antimicrobials and degradative enzymes
- release histamine
What is the function of eosinophils?
- phagocytes
- larger than basophils and neutrophils
- granulocytes
- release antimicrobials and degradative enzymes
- release histamine
What is the function of dendritic cells?
- antigen presenting
- activate T and B cells
- mature dendritic cells can prime naive T cells
What is the function of natural killer cells?
- granulocytes
- release lyric granules which kill infected cells
- hold back infection until adaptive immunity kicks in
- link innate and adaptive immunity
- produce cytokines
What is the function of T cells?
Cellular immunity
Where are T cells produced?
Bone marrow
Where do T cells mature?
Thymus
What are the CD4+ cell subsets?
TH1
TH2
TH17
TFH
Treg
What is the function of TH1?
Support macrophages
What is the function of TH2?
Supports humoral response
Function of TH17?
Supports innate immune response
Secrets IL-17,22
Function of TFH?
Supports humoral response
Function of Treg?
Suppress T cell activity and prevent autoimmunity
Function of B cells?
Humoral response
Describe innate immunity
- first line of defence
- non-specific
- short lasting
- immediate
Where are B cells produced?
Bone marrow
Where do B cells migrate to once they are produced?
Via the blood to the spleen or lymph nodes
What is the function of B cell receptors?
Bind to antigens
What is an antigen?
Foreign substance
What are the sequence of steps which occur following an antigen binding to a B cell receptor?
- antigen engulfed into the B cell
- B cell breaks down the antigen and the products are placed on the surface of the B cell in major histocompatibility complexes II (MHC II)
- these allow CD4+ T helper cells to bind
- this releases lymphokines
- this causes B cells to differentiate into plasma cells which release antigens
What is the function of T helper cells (CD4)?
Bind to MHC II on B cells
What is the function of cytotoxic T cells (CD8)?
Bind to MHC I on virally infected cells
- this secretes cytotoxins which induces apoptosis
What do all cells with a nucleus contain?
MHC I in their membrane
What is the function of memory T cells?
They can initiate a very rapid response if they have encountered the antigen before
Role of epithelium in innate immunity?
- physical barrier
- antimicrobials peptides
- cytokines/chemokines
- IgA
- lactoferrin
- lysosomes
- cystains
What are examples of antimicrobial peptides?
- B defence
- HNPs
What is the function of antimicrobial peptides?
- modulate immunity
- destroy pathogens
What is IgA?
- an immunoglobulin
- produced at the mucosal surface
- binds to bacterial cell flagella preventing motility
- opsonisation
What is opsonisation?
Coating of microbes for host recognition
What is the function of chemokines?
Cell recruitment and chemotaxis
What is the function of cytokines?
Cell activation
What are the main type of T cell receptor?
Toll like receptors
What are the main receptors in periodontitis?
TLR2 and TLR4
What type of microbe can enter the cell?
Viruses
What do dentin and glucagon receptors recognise?
Fungi
What do NOD like receptors recognise?
Bacteria
PRR PAMP
Pattern recognition receptors recognise pathogen associated molecular patterns
What do PARs recognise?
Microbial and allergens
What is the function of lactoferrin?
Antimicrobial and transports iron ions
What is the function of lysozymes?
Attacks bacterial cell walls
What is the function of cystains~?
Anti-protease activity
What are the sequence of steps in phagocytosis?
- chemotaxis transport phagocytes to microbe
- adherence
- phagocyte ingests the microbe
- phagosome formed
- phagolysosome formed
- enzymes digest the microbe
- waste is discharged
What are examples of professional antigen presenting cells?
Macrophages and dendritic cells
What are examples of phagocytes?
- neutrophils
- dendritic cells
- mast cells
- macrophages
- eosinophils
What are the three types of cell adhesion molecules?
- selectins
- integrins
- immunoglobulins
What are examples of granulocytes?
- mast cells
- natural killer cells
- monocytes
- macrophages
- neutrophils
What are the 4 main roles of the innate immune system?
- recognise pathogens
- engulf and destroy pathogens
- alarm other immune cells to fight pathogens
- coordinate with the adaptive immune component
How are pathogens recognised by the innate immune cells?
Pathogen associated molecular patterns are recognised by pattern recognition receptors
Describe adaptive immunity
- specific
- acquired
- not immediate
When does adaptive immunity kick in?
When the threshold level of antigen is reached
What type of chains feature on T cell receptors?
Alpha and beta mainly
What is the process in which T cell receptors are rearranged?
Somatic recombination
What enzyme drives somatic recombination?
RAG
What is the function of somatic recombination?
Leads to different receptor structures which are able to recognise different antigens
Where is thymic education carried out?
In the thymus
How do the T cells get from the bone marrow to the thymus?
The thymus secretes chemokines which draws the T persecutor cells towards the thymus (chemotaxis)
What is the thymus?
Primary lymphoid organ gland
What happens to the T cell persecutors in the thymus?
- ## T cell receptors and recombination presented on surfaces, both CD8 and CD4 proteins on surface
What does MHC stand for?
Major histocompatilbilty complex
What is positive selection?
When MCHs recognise CD4/CD8 effectively
What happens if during positive selection, the MHCs don’t recognise the CD4/CD8?
Apoptosis
What is the step after positive selection?
Negative selection
What is negative selection?
- MHCs have self peptides displayed
- if TCRs recognise the self peptides then apoptosis is induced
- prevents autoimmunity
What happens after negative selection?
The T persecutor cell with either react with the MHC I or MHC II molecule
What is the name for a T cell which reacts with MHC II?
T helper cell (CD4)
What is the name for a T cell which reacts with MHC I?
Cytotoxic T cell (CD8)
How are T regulatory cells produced?
- some T helper cells and Cytotoxic cells can become T regulatory cells
- AT THIS STAGE THE T CELLS ARE STILL NAIVE
What are the signals required for T cell activation?
- TCR interaction with MHC of antigen presenting cell
- costimulation
- cytokine production
What are B cell receptors?
Immunoglobulins
What type of chais do B cells have?
Heavy and light
What type of selection do B cells undergo and where?
Negative selection in the bone marrow
What happens in B cell negative selection?
- if a B cell reacts with a self antigen it is retained in the bone marrow and phagocytosed by macrophages
- if a B cell doesn’t react with a self antigen it moves into the blood and expresses IgD and IgM
What is the most numerous immunoglobin?
IgG
Which immnoglobin has 10 binding sites?
IgM
Which imunoglobins have high affinity?
IgG and IgE
What is the function of IgE?
Allergy
What are immunoglobins?
Antibodies
What are three functions of antibodies to prevent microbial activity?
- neutralisation
- opsonisation
- initiation of the classical pathway of complement
Where are B cells activated?
In lymph nodes
What are the two types of B cell activation?
- thymus dependant
- thymus independent
Which type of B cell activation produces memory B cells?
Thymus dependant
Where do B cells mature?
Bone marrow
Describe the process of B cell activation
- B cell is triggered when encountering its matching antigen
- B cell engulfs the antigen and digests it
- B cell displays the antigen fragments bound to its MHCs
- this MHC- antigen complex attracts a matching mature T cell
- cytokines are secreted by the T cell which help the B cell to multiply and differentiate into antibody producing plasma cells or B memory cells
-in plasma cells these antibodies are released into the blood in order to lock onto matching antigens which are cleared from the body
What is the different in life length of plasma cells and memory B cells?
- memory B cella can live for decades
- plasma cells are short lived
What is the function of memory B cells?
If a memory B cell encounters a previously encountered enticed it will divide rapidly and make plasma cells which results in a large number of antibodies to destroy the pathogen
What does clinal selection produce?
B memory cells and plasma cells
How many chains are antibodies made up of?
4 (2 heavy 2 light)
Where do B cells and T cells communicate?
Germinal centres
What is the function of immunological tolerance?
Safeguard mechanism to prevent the production of auto reactive cells
What are the 5 cardinal signs of inflammation?
- redness
- heat
- swelling
- pain
- loss of function
What are the stages of inflammation?
- initiation
- progression
- amplification
- resolution (acute)
- no resolution (chronic)
What is the vascular response to acute inflammation?
- dilation of small BV
- leaky vessels (exudation) to increase vascular permeability leading to an influx of inflammatory infiltrate (oedema)
Describe the complement system?
- activated by one of three pathways
- classical/alternative/lectin
- all activate C3
- C3 convertase produces C3a and C3b
- C3b is responsible for opsonisation
- C3a is responsible for the production of anaphylatoxins
- C5a attracts macrophages and neutrophils
What is the classical pathway triggered by?
Antibody attaching to microbe
What is the alternative pathway triggered by?
Microbial cell wall
What is the lectin pathway triggered by?
Carbohydrates on the pathogens surface
What is the role of anaphylatoxins?
- smooth muscle contraction
- leaky capillaries to increase inflammatory infiltration
What are common causes of inflammation?
- infection
- hypersensitivity
- physical/chemical agents
- tissue necrosis
What cells release histamine?
- mast cells
- basophils
- platelets
Sequence of steps in acute inflammation
blood flow changes
- constriction to control blood loss
- dilation to increase blood flow to tissue
- histamine release increases permeability and formation of an exudate
- circulation is slowed
Exudation of fluid- plasma proteins to site
- starlings law
Cellular phase
- neutrophils (C5a)- remove pathogens
Describe the kin in system
- activated by hageman factor
- activated kallikrein which converted kininogens to kinins eg bradykinin
- kinins cause:
Vasodilation
Activate complement
Chemotaxis for neutrophils
Increase blood vessel permeability
What’s an example of a kinin?
Bradykinin
What are the three coagulation pathways?
- extrinsic
- intrinsic
- common thrombin
What triggers the extrinsic coagulation pathway?
Damaged blood vessels
What triggers the intrinsic coagulation pathway?
Blood coming into contact with sub-endothelial connective tissue
What triggers the common thrombin coagulation system?
Production of thrombin
What is haemophilia?
When blood doesn’t clot properly
What is the function of the fibrinolytic system?
To prevent excess blood clotting
Describe the fibrinolytic system
- kallikrein converts plasminogen to plasmin
- plasmin converts fibrin to fibrin degradation products
Which two organs cannot repair?
The heart and liver
What is suppuration?
Formation of an abscess
- up sis a collection of dead bacteria and dying neutrophils
What are the ways in which chronic inflammation can arise?
- take over from acute inflammation
- de novo eg autoimmune
- develop alongside acute inflammation
What are the hallmarks of chronic inflammation?
- neutrophils are replaced with macrophages and lymphocytes
- tissue destruction
- healing
What is an example of non-specific chronic inflammation?
Periodontitis
What is an example of specific chronic inflammation?
Rheumatoid arthritis
What causes cloudy swelling?
Influx of sodium and water
What causes fatty change?
Accumulation of lipid vacuoles in th cytoplasm
What are four types of tissue necrosis?
- co-agulation
- liquefactive
- caseous
- fibrinoid
What is hypoxia?
Deficient oxygen delivery to tissue
What is ischaemia?
Deficient blood flow to tissue
What are the stages in healing?
- coagulation
- inflammation
- proliferation
- maturation
What is repair vs regeneration of tissue?
- repair is done during chronic inflammation
- regeneration is rebuilding up the tissue done in acute inflammation
What are liable cells and an example?
Rapid regeneration cells eg epithelial cells
What are stable cells and an example?
Regenerating cells eg liver and kidney cells
What are permanent cells and examples?
Permanent cells eg heart and muscle cells
What occurs during the proliferation stage of tissue healing?
- formation of granulation tissue (vascular and fibrous)
- angiogenesis
What occurs in the maturation stage of tissue healing?
Tissue remodelling
What are the stages in fracture healing?
- inflammation
- repairing
- remodelling
What is hypersensitivity?
State of altered reactivity where the body reacts with an exaggerated immune response to a foreign agent
What is the most common type of hypersensitivity?
Type 1
What is the most rapid type of hypersensitivity?
Type 1
What is type 1 hypersensitivity to do with?
Allergy
What is an example of type 1 hypersensitivity?
Anaphylaxis
What is type II hypersensitivity?
Cytotoxic
What is an example of type II hypersensitivity?
Acute transfusion reaction
What is type III hypersensitivity?
Inflammatory response- complement system activated
What is an example of type III hypersensitivity?
Rheumatoid arthritis
What is type IV hypersensitivity?
- cell mediated
What is an example of type IV hypersensitivity?
Contact dermatitis
Benign vs malignant neoplasia
Benign
- encapsulated therefore growth is localised
- resembling tissue of origin
Malignant
- no capsule therefore metastasis
- many mitoses
Treatment of benign neoplasia?
Local excision
Treatment of malignant neoplasia?
- local excision
- radio therapy
- chemo therapy
Suffixes meaning malignancy?
-carcinoma
-sarcoma