HUBS191 Immunology

What is the immune system made of

Organs

Cells

Molecules

What is the immune system

An organised system that interacts together to defend the body against disease

What makes up the Primary lymphoid organs

Bone marrow and the thymus

What does bone morrow do in respect to the Immune system

Its a source of stem cells that dev into cells of the innate and adaptive immune responses

What does the thymus do with respect to the immune system

- "school" for white blood cells called T cells

- Developing T cells learn not to react to self

What would happen if T cells did react to self

Autoimmune disease would occur

What makes up the secondary Lymphoid system

Lymph nodes and the spleen

What does the spleen do with respect to the immune system

it is the site of initiation for immune responses against blood-borne pathogens

Where are the Lymph nodes Located

- Located along lymphatic vessels

What does the Lymph nodes do with respect to the immune system

-lymph fluid from blood and tissue is filtered

- Site of initiation of immune responses

What are the three layers of defence

1. Chemical and physical barriers

2. Innate arm

3 Adaptive arm

What is the first physical barrier in the immune system

The skin

What are the layers of the skin

The epidermis

The dermis

What are the chemical defences of the skin

Antimicrobial peptides

Lysozyme

Sebum

Salt (sweat)

How does lysozyme defend the body

Breaks down bacterial cell walls

How does sebum defend the body

It has a low pH (Acidic) which helps prevent microbial growth

How does sweat help defend the body

Contains salt which is hypertonic and dehydrates the pathogen

Where does mucus get produced

By goblet cells

What are the layers of the mucous membrane

Mucus layer

Epithelium

Fibrous connective tissue

how often are the epithelium cells renewed

Constantly

Where are the mucosal membranes

In the face area

Respiratory

Gut

Urogenital/rectal

Describe the Mucociliary escalator

Mucus catches dirt and Cila in rythym "brush" the mucus up to the pharynx to couch it out

What are the chemical defenses in the body

Stomach - low pH

- Gall Bladder - Bile

- Intestine - Digestive enzymes

- Mucus

- Defensins

- Lysozyme (tears, urine)

What are examples of Innate defences

Skin

Mucous membranes

Phagocytes

Natural killer cells

Inflammation

Antimicrobial proteins

Fever

What are examples of Adaptive defences

B cells and T cells

What are the features of Innate immunity

- Already in place

- Rapid

- Fixed

- Limited specificites

- Has no specfic memory

What are the features of Adaptive Immunity

- Improves during the respones

- Slow days to weeks

- Variable

- Highly specific

- Has long term memory

What is blood made out of

55% plasma, 45% formed elements

What are formed elements

Platlets,

white blood cells,

Red blood cells

What are myeloid and Lymphoids derived from

Hematopoietic stem cells in the bone marrow

What do Myeloids lead to

Red blood cells

Granulocytes

moncytes

Dendritic cells

Platelets

What do Lyphoids lead to

B and T Lymphocytes

what are Neutophils

Leukocytes

(Higly phagocytic)

what happens to the number of Neutrophilsdurong infection

It increases

What do Granulocytes do

Circulate in the blood and can move into tissue during inflammation

Where are Mast cells found

Lining the mucosal surfaces

What do Mast cells do

Release granules (chemical signal) that attract white blood cells to areas of tissue damage

What are the immune cells found in the blood

Ganulocytes

Monocytes

Dendritic cells

Platelets

B Cells

T Cells

Where are monocytes present

In the blood

When do monocytes have a low phagocytosis

When they are in the blood

How do Monocytes turn into Macrophage

When they leave the blood

What are the three functions of a Macrophage

1. Phagocytosis

2. The release of chemical messengers

3. Show information about pathogenic microbes to cells

How are and where are Denritic cells found

In low numbers in the blood and all tissues in contact with the enviroment

Are Dendritic cells low or high phagocytic

High

What is the most important part of a denritic cell

To help trigger adaptive immune responses

How do cells of the immune system move around the body

Cells are carried in the blood and in the lymph

Cells can leave blood to enter tissues

Lymph in tissues collects into lymphatic vessels. these drain lymph into lymph nodes

How do innate cells reconginse

They look for PAMPS which then set off chemical signals

What does PAMPs stand for

Pathogens-associated molecular patterns

What are the comman building blocks of Viruses

Nucleic acids : ssRNA and dsRNA

What are the comman building blocks of Bacteria

Cell wall : (LPS)/Endotoxins, lipoteichoic acid

Flagella:flagellin

Nucleic acid : unmethylated CpG DNA

How is a fever induced

Fever is provoked by interleukins released during phagocytosis of certain bacteria

What are the key componets of the inflammatory response

Bacteria breaks through skin

Bacteria gets detected by Chemical signals (within the skin)

Nuetrophills are sent to location

Nuetrophils break through the capiillay walls

then follow the chemical trail to injury site

What is stage one of Phagocytosis

1. Phagocyte adheres to pathogens or debris

What is the second stage of phagocytosis

The bacteria is fully englufed by the Pseudopods that then forms a phagosome

What is the third step in phagocytosis

Lysosome fuse with the phagocytic vesicle, forming a phagolysome

What is the fouth step in phagocytosis

Toxic compouds and lysosomal enzymes destroy pathogens

What is the Fith step in phagocytosis

Exocytosis of the vesicles removes indigestible and residual material

What does the killing and digestion of phagocytosed microbes require

Low pH

Reactive oxygen and reactive nitrogen intermediates

Enzymes for proteins, lipids and nucleases

What are the 3 complement pathways

Classical, alternative and lectin

What are the three outcomes of the Complement pathways

Label, Destroy and Recruit

Breifly describe The Classical pathway

Antibody bound to pathogen binds to complement

Breifly describe The Alternative pathway

PAthogen binds complement to surface/pathogen component

Breifly describe The Lectin pathway

Carbohydrate components of microbes bind complement

Breifly describe The Label/Opsonisation outcome

Opsonisation = coating of a microbe with either a anitbody and/or a complement fragment C3b

Breifly describe The Recruit outcome

Phagocytes attracted into site

mast cells degranulated by C3a and C5a

Inflammatory mediators released inculding proteins that attract phagocytes

Breifly describe The Destroy outcome

Microbes coated withC3b are phagocytosed

Assembly of the MAC causes lysis

What are the major methods of immune cell communication

Soluble molecules Binding to a receptor

Cell surface-bound receptors

Antigen (pathogen part)

Explain Chemical messengers binding to receptors

cytokine binds with cytokine receptors (differs per case) can increase or decrease gene expresion

Explain surface-bound receptors binding to cell surface bound ligands

can alter function of one or both (very special handshake)

Explain antigen communication

A dendritic cell (antigen pocessing) poccess the antigen of which binds to a T cell and that activate its

What is an antigen?

Anything that can be recogised by the immune system

What is a foreign antigen

Anything from the outside

What is a self antigen?

Immune system usally tolerant of self-antigen

What does MHC stand for

Major histocompatiblity

What are the two types of MHC

MHC I and MHC II

What is MHC I

Presents endogenous (intercellular) antigen. Expressed on all nucleated cells.

What is MHC II

MHC II presents exogenous (extracellular) antigen. Expressed only on antigen presenting cells such as dendritic cells.

What are Cytokines

Cytokines are molcules such as interleukins and interferons that control growth and activity of immune cells

What are Chemokines

Chemokines are molecules that stimulate cell migration

What are the simularities of Cytokines and Chemokines

Both aer produced by innate and adaptive immune cells as well as cells that infulence the immune system (e.g epithelial cells)

How do T cells that have been activated by the dendritic cell help a B cell

- Via making cytokines that bind receptors on B cell membranes

- Have cell surface-bound receptors that bind to a B cell surface-bound ligand (or vice versa)

What does the communication between an activated T cell and a normal B cell

Leads to the activation of the B cell and helps the B cell to make antibodies

What can a antibody binding to a pathogen trigger

The classicla pathway of complement activation

Complement fragemtns that are bound to antigen can also help activate B cells to make antibodies

where do B cells develop

In the bone marrow

What is the unique receptor of a B cell

BCR or a secreted antibody

what are plasma cells in terms of B cells

They are activated B cells that secrete antibody

what can a B cell provide

memory

what males up an antibodys structure

Antigen binding sites

Light and heavy chains

variable and constant regions on the chain

disulfide bridges connecting the light and heavy chains

What is the surface of a B cell covered with as far as antibodies concern ?

IgM and IgD

what does BCR stand for

B Cell Receptor

The BCR Binds to ______ and activates the ____

Antigen, B Cell

How is the BCR anchored

via a transmembrane domain (TM). secreted antibodies lack TM

what are the three functions of an antibody

1. Neutralisation - Can bond and make toxins less toxic

2. Opsonisation - To make tasty to phagocytes

3. Complement activation

Describe what Virial neutralization is in terms of structure

The antibody binds to the virus covering all the active sites so the virus can't bind to other cells

Describe what Opsonisation is in terms of structure

the bacteria really slippery we use antibodies to make the structure more suceptible to be eaten by the macrophage

what is an Epitope

an epitope is an antibody bonding site

what does the term native antigen mean

it means that the antigen does not have to be processed to peptide (or in the context of MHC

explain the activation of complement system and pore formation

the complement proteins will attack the membrane of the forgein cell and make a pore allowing the flow of water and ions, flooding the cell.

what is the shape of IgG antibody

A monomer

What is the distribution level IgG

It is the most abundant Ig class in blood