Lecture 1 (Week 1A) - Introduction Flashcards by Kate pline

Why is immunology important and interesting?

it is of fundamental importance for life
immunology underpins vaccination
immunological techniques underpin many diagnostic technologies
many of the diseases of the modern world are caused by the immune system going wrong

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The answer to most immunology questions is

“it depends”

• context is everything!!!

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Important features of the immune system

• complexity
• redundancy
• its basic function is to distinguish between
SELF vs NON-SELF

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The basic function of the immune system is

to distinguish between SELF and NON-SELF

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Even low-grade pathogens find us nourishing

bacteria in the gut (10,000 species)
Staphlycocci on skin
Klebsiella/Neisseria/Pneumococci in throat
• when they get into the wrong place, without an immune system, we die
• even with an immune system they can still kill us

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HIV kills

immune cells (T-cells)
• patients die of opportunistic infections
(Pneumocystis carinii, Cryptosporidium, atypical Mycobacteria_

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The immune system is very complex, with lots of different potential problems, but the most extreme phenotype is

lack of lymphocytes

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SCID

severe combined immune deficiency
• lack of lymphocytes
• lots of causes

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A baby with SCID may have

recurrent bacterial, viral, or fungal infections
that are much more serious and 
less responsive to treatment
than would normally be expected.
These can include
• ear infections (acute otitis media)
• sinus infections (sinusitis)
• oral thrush (a type of yeast infection in the mouth)
• skin infections
• meningitis
• pneumonia
• infants with SCID may also have chronic diarrhea

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The cells of the immune system come from

a stem cell in the marrow

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T cells mature in the

thymus (hence T)

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B cells are so-called because

they were identified in the chicken Bursa

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In mammals, most b cells are made in

bone barrow

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Primary lymphoid tissues

Bursa

Thymus
• capsule
• thymic corpuscle
• thymic lobule
• cortex
• medulla
• interlobular septum

(ask about bone marrow)

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Secondary lymphoid tissue

tonsils
lymph nodes
lymphatic vessels
liver
spleen
Peyer’s patch on small intestine
appendix

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Key basic concepts in immunology

the immune system recognizes pathogens by responding to non-self
an antigen is anything which elicits an adaptive immune response
• self antigen
• foreign antigen
the adaptive immune system shows exquisite specificity
like the brain, the immune system has memory

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The immune system recognizes pathogens by

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responding to non-self

• self vs non-self

An antigen is

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anything which elicits an adaptive immune response
• self antigen - when the immune system goes awry and starts responding to self
• foreign antigen - when the antigen comes from outside you

Self antigen

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when the immune system goes awry and starts responding to self

Foreign antigen

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when the antigen comes from outside you

Immune cells need to respond to foreign molecules (pathogens) - they use

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surface receptors

Lymphocyte (T or B)
• antigen specific T cell receptor
• antigen specific B cell receptor
-->
massive cell division then effector function
(adaptive immunity)

Phagocyte
• pattern recognition receptors
• Fc receptors
--> 
do their business immediately
(innate immunity)

Surface receptors - Lymphocyte

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Lymphocyte (T or B)
• antigen specific T cell receptor
• antigen specific B cell receptor
-->
massive cell division then effector function
(adaptive immunity)

Surface receptors - Phagocyte

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Phagocyte
• pattern recognition receptors
• Fc receptors
--> 
do their business immediately
(innate immunity)

In health, white cells are

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in blood and lymph nodes

* not in tissues

Innate immunity eg step on nail

normally, neurophil in blood remains in vessel ``` step on a rusty nail (how does the host know the infection is there?) • neurophil in blood leaves vessel --> bacteria phagocytosed and killed • endothelial cells cytkines increase adhesion molecules • vessel becomes sticky ```

Pathogen-associated molecular patterns

* gram + and gram - bacterial cell wall * virus * bacterial flagella * eukaryotes (us)

The Toll-like receptors

molecules on the surface of mammalian cells which recognize components of bacteria and viruses to alert the immune system • 10 of them --> cell becomes activated and starts to make pro-inflammatory cytokines

A spot is

inflammation and tissue injury caused by white cells leaving the blood and going into a follicle to kill skin bacteria growing in the wrong place

Acne

inflammation is when white cells leave the blood and move into the tissues - and in the process of getting rid of the bugs, kill normal tissue as well • neutrophils produce, and are full of, dangerous molecules and die in tissues --> destroys normal tissue as well

Ulcerative colitis

* neutrophils * crypt abcesses * usually superficial * organ specific

Adaptive immunity

* at birth we already have T and B cells which can recognize billions of different foreing antigens, wo we are ready for any infections * but as there are 10^13 cells in our body, we cannot devote them all to the immune system * if we have 10^11 lymphocytes which can respond to 10^10 antigens, it means we only have a few cells for each antigen * so we need to make sure these cells see a pathogen quickly, and really get going fast - or else you die

We have T and B cells that recognize

harmful non-self but not many (adaptive immunity)

What happens when a B cell becomes activated?

Clonal expansion T cell help Memory Make protective antibodies

Clonal expansion (T cells) controlled by

IL-2 Mediate immunity Memory

Vaccination - the triumph of

immunological memory • Edward Jenner (1749-1823) • noticed that milkmaids who caught cowpox did not get smallpox • scraped fluid from a cowpox blister into the skin of 8yrold James Phipps who got a bit sick and recovered • Phipps was then immune to cowpox and smal pox

After vaccination we respond

make more lymphocytes for the vaccine-memory cells | are also "primed"

Modern immunology is all about

communication | • cells have to know where they are and what is around them

Cells have thousands of different receptors to

sense the environment • other cells • hormones (chemical messengers) • extracellular matrix

Receptors transmit signals from

the cell surface | to the nucleus to change gene expression and function

Inverse relation between the

incidence of prototypical infectious diseases and incidence of immune disorders from 1950-2000

Complex inflammatory diseases of the modern world

``` overactivity of the immune system • Crohm's • psoriasis • rheumatoid arthritis • ulcerative colitis ``` ``` asthma allergies autoimmune diseases eg • type 1 diabetes • multiple sclerosis • SLE ```

Lecture 1 (Week 1A) - Introduction Flashcards

(41 cards)