Immunity

Antigens

Molecules that generate an immune response when detected by the body

Antigens that aren’t normally found in the body

Foreign antigens

Antigens allow the immune system to identify:

• Pathogens

• Abnormal body cells

• Toxins

• Cells from other individuals of the same species

Acronym for immune response

pep pat tab pa

Pep pat tab pa meaning

Phagocyte engulfs pathogen, phagocyte activates t cells, t cells activate b cells, plasma makes more antibodies

What is the pathogen contained in during phagocytosis

Phagocytic vacuole

What fuses with the phagocytic vacuole in phagocytosis

A lysosome

What do lysosomes contain

enzymes called lysozymes

How are pathogens broken down in phagocytosis

the lysozymes in lysosomes break down the pathogen

How is a t-cell activated?

It has receptor proteins that bind to complementary antigens

what do helper t-cells do

Release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells

Cytotoxic T-cells function

Kill abnormal and foreign cells

B-cells function

Secrete antibodies

When antibodies and antigens bind it is called an

antigen-antibody complex

Clonal selection

• B-cell antibody meets complementary antigen, binds to it

• B-cell is activated

Activated b-cell divides into

plasma cells

Plasma cells secrete

Monoclonal antibodies

How many binding sites does an antibody have?

two

Agglutination

pathogens clumped together

Each antigen has a variable region with a unique…

tertiary structure

An antigen is a…

protein

All antibodies have the same…

constant regions

What bond is in an antigen?

Disulfide bridge

Cellular response

• T-cells and other immune system cells they interact with

Humoral response

• B-cells

• Clonal selection

• Production of monoclonal antibodies

Primary response

When an antigen enters the body for the first time

Primary response characteristics

• Slow

• Symptoms shown

• Memory cells produced

Secondary response

When the same pathogen enters the body again

Secondary response characteristics

• Quicker and stronger

• Clonal selection is faster

• Usually no symptoms

Two types of active immunity

• Natural

• Artificial

Active immunity

Where your immune system makes its own antibodies

Active Natural immunity

When you become immune after catching a disease

Active Artificial immunity

When you become immune from a vaccination

Two types of Passive immunity

• Natural

• Artificial

Passive immunity

Immunity from being given antibodies made by a different organism

Natural passive immunity

Baby becomes immune due to antibodies it receives from its mother (placenta and breast milk)

Artificial passive immunity

Become immune after being injected with antibodies from someone else

Benefits of active immunity

• Memory cells are produced

• Protection is long term

Cons of active immunity

• Requires exposure to antigen

• Takes a while for protection to develop

Benefits of passive immunity

• Doesn’t require exposure to antigen

• Protection is immediate

Cons of passive immunity

• Memory cells aren’t produced

• Protection is short term as antibodies are broken down

Vaccines contain antigens that cause your body to produce

Memory cells against a particular pathogen

Herd immunity

Unvaccinated people are protected as the disease is spread around less due to more people being vaccinated

Disadvantage of taking a vaccine orally

• Could be broken down by enzymes in the gut

• Molecules may be too large to absorb

Ethical issues surrounding vaccines

• Vaccinations are tested on animals first

• Some vaccinations may include animal products

• If there’s an epidemic how is it decided who gets the vaccine first?

Antigenic variation

Where some pathogens change their surface antigens as to not be recognised by the immune system

Examples of pathogens that show antigenic variation

• HIV virus

• Influenza virus

Monoclonal antibodies

Antibodies produced from a single group of genetically identical b-cells

Monoclonal antibodies all have an identical

structure

Monoclonal antibodies for treating cancer

• Cancer cells have antigens called tumour markers

• Attach anti-cancer drugs to complementary monoclonal antibodies'

• The drug will only accumulate where the cancer cells are

• Low level of side effects because only accumulate on specific cells

What hormone do pregnancy tests look for

hCG

The application area on a pregnancy test contains

antibodies that are complimentary to hCG, bound to blue beads

The test strip of a pregnancy test contains

Antibodies to hCG that are immobilised

If no hCG is present in a pregnancy test,

the blue beads will bypass the immobilised antibodies

ELISA test

Allows you to see if a patient has any antibodies to a certain antigen, or any antigen to a certain antibody

Direct ELISA test

• Antigen attached to well

• Antibody with enzyme added, wash

• substrate added

• Coloured product formed

An indirect ELISA is used to identify

HIV

How does an indirect ELISA work?

• HIV antigen bound to well bottom

• Sample of blood added, if there are HIV specific antibodies, these bind to antigen

• Well is then washed to remove unbound antibodies

• A secondary antibody is added, which is attached to an enzyme

• This binds to the HIV-specific antibody

• Well is washed

• Solution added to the well that contains a substrate complementary to the enzyme, a coloured product is formed

Ethical issues of using monoclonal antibodies

• Animals are used to produce the cells from which the monoclonal antibodies are produced.

HIV infects and kills which cells?

helper t-cells

HIV host cells

helper t-cells

Latency period of HIV

Infected person won’t experience any symptoms

Initial symptoms of AIDS

Minor mucous membrane infections and recurring respiratory issues

Factors that affect progression of HIV to AIDS and survival time with AIDS

• Age

• Healthcare access

• The strain they’re infected with

• Existing infections

HIV structure

• An envelope with attachment proteins

• Inside envelope, Capsid

• Inside capsid, RNA and reverse transcriptase