L18 - intro to immunity

Immunity

The ability of an organism to resist a particualy infections or toxin by the action of specialised cells or molecules

How do we gain immunity

Activate and passive

Active natural immunity

Natural immuntiy from infeciton

Active artificial immunity

Immunisation

Passive natural immunity

Placental transfer of maternal IgG

Passive artifical

Human IgG

Types of immunity (2)

• Innate

• Acquired/ adaptive

Innate immunity features (8)

• present from birth

• Simialr recognition systems

• Limited capcity

• There before infection starts

• Patrols for infection

• Recognises common danger signals

• Rapid response

• No memory

Adaptive/acquired immunity features (6)

• not present from birth

• Learns from invading organisms

• Sophisticated highly specific recognition

• Specific memory

• Slower response

• Activated in immune organs

Goals of immune system (6)

• clear potential pathogens in a controlled and efficient process

• Activate for appropriate duration

• Potentially confer future protection

• Non attack self

• Remove any non healthy cells eg tumours

Factors affecting immunity (8)

• general health

• Infection

• Nutrition

• Adverse environmental conditions

• State of microbiome

• Pregnancy

• Genetic disorders

• Stress

What was the first vaccine

Edward jenners small pox vaccine

What are vaccines an example of

Artifical active immunity

What are vaccines

A substance used to stimulate the production of of antibodies and provide immunity against one or several diseases prepared from the causative agent of a disease of a synthetic substitute

Who can immunisation protect

The individual and the population → disease declines if thee majority of population is immune

What % of the population needs to be vaccinated for herd immunity

>95%

What happened in 1998

Dr Andrew Wakefield published a false link of mmr to autism leading to a high dorp in vaccinations

Troubles with vaccinations

Takes time to develop, constantly evolving organism, clinical trials,production, expensive

Types of vaccines (4)

• live (attenuated)

• Killed (inactivated/ attenuated)

• Subunit

• Nucleic acid

How long does it take to see an antibody being produced against an inital infection

7 days

Types of immunity (2)

• humoral

• Cellular

Humoral immunity

Macromolecules found in extracelllar fluid

What cells produce antibodies

Plasma cells whcih are mature b lymphocyte cells

What parts of an antibody are there

Light chain, heavy chain, variable region, constant region

Where do all cells come from

Pluripotent haematopoetic stem cells

Which cells come from common lymphoid progenitor (5)

• b cell

• T cell

• NK cell

• ILC

• Immature denderitic cell

Which cells come from teh common myeloid progenitor (10)

• granulocyte/macrophage

• Megakaryocyte

• Erythroblast

• Immature dendritic cells whcih are

• Neutrophil

• Eosinophils

• Basophils

• Monocyte

• mast cell

• Macrophage

What is used for developemtn of the adaptive immune repsonse

Clonal selection

Stages of clonal selectrion (4)

• a single progenitor cell gives rise to a large number of lymphocytes each with a differnt specificity

• Removal of potentially self reactive lymphocytes by clonal deletion

• Pool of mature naive lymphocytes

• Proliferation and different tío an of activated specific lymphocytes to form a clone of effector cells

• Effector cells eliminate antigens

How do immune cels circulate

Via blood and lymph

Primary lymphoid tissues (2)

Thymus, bone marrow

Bone marrow

The soft spongy, highly cellular tissue that fills teh internal cavity of the bones

Thymus

A specialised and hihgly cellular gland that produces T cells

What happens in the Bone marrow (2)

• b and T cells continually develop

• B cells mature

• T cells leave to the thymus to mature

What diversity is the bone marrow

Is clonally diverse → each cell has a singel specificity of receptor + cells are specific to the antigens

What happens int he thymus

T cells are educated bu onyl 2-4% survive and exit to secondary lymphoid tissues

Why are mature lymphocytes clonally diverse

Each cell has receptors specific to a single antigen

Examples of secondary lymphoid tissues (4)

• spleen

• Lymph nodes

• Tonsils

• Mucosal associated lymphoid tissues (MALTs)

What only happens in the secondary immune organs

Teh adaptive immune repsonse

Once they are developed what do b and T lymphocytes do

Recirculate and if they meet an antigen they undergo clonal expansion ad differniation in the tissue s

What do the lymph nodes do (2)

• trap bacteria, viruses and baronial cells ensuring they come into contact with the immune cells

• Cleans lymph and returns it to the system

What is the germinal centre of the lymph nodes

A specialised strucutre where b cells diffentiate, proliferate and mutate antibody genes, producing antobody secreting cells

What is MALT

Mucosa associated lymphoid tissue which is a diffuse system of non encapsulated submucoseal lymphoid tissue int he intestinal and repsiraoty tract

Examples of respiraoty MALTs

Nasopharyngeal lymphatic tissue eg tonsils and adenoids

Intestinal MALTs

Peters patches,appendix and isolated follicles in intestinal mucosal

How are peyers patches unique compared to other 2nd lymphoid systems

Are in constant contact with external antigens and have specialised m cells allowing some antigen thorugh so the cellls within can response

Current understanding of the immune system (6)

• the imune system involves innate and adaptive

• Has cellular and huoural elements

• Has different receptors

• Different repsonses against infections

• Complex interactions

• Has controls in place

What do different effector mechanisms that are needed depend on (4)

• the type of pahtogen

• Localisation

• Stage of infection

• Challenge