11.1 Flashcards
what is an antigen
any foreign molecule that can trigger an immune response
every organism has unique cell surface
- the proteins and glycoproteins on our own cells are recognised as self-antigens
- our body can distinguish b/w self antigens and foreign antigens and thus only foreign antigens trigger an immune response
blood donation
antigens on the surface of blood stimulate antibody production in a person with a different blood type
blood group A has A antigens and anti-B-antibodies
blood group B has B antigens and anti-A- antibodies
blood group AB has A & B antigens and neither antibodies
blood group O has neither antigens but both A & B antibodies
why are some pathogens species specific
- many pathogens bind to receptors on cell membranes which are only present in a specific species
- some toxins produced by bacteria have specific target sites which are only present in specific species
- some pathogens may require certain body temperature which is only in one species
zoonotic
- is a disease from animals that can be transmitted to humans
- eg covid from bats, rabies from dogs
- cause for global concern as animals are living more closely with humans due to environmental issues
antibody production
- the first leukocyte to encounter an antigen is usually a macrophage. when a macrophage encounters a possible pathogen it engulfs it by endocytosis, partially digests it and displays molecular pieces of it on its cell membrane attached to MHC proteins. known as antigen presentation
- a lymphocyte known as helper T cells have receptors which bind to the antigens on the macrophage. the helper t cells become activated and change the immune response from non-specific to antigen- specific
- helper t cells activate lymphocytes called B cells which produce antibodies for the identified antigen. they then divide by mitosis to form clone of cells known as a plasma cell. these have extensive networks of RER which synthesis large quantities of antibodies to be secreted by exocytosis
- some cloned b cells become memory cells which remain in blood to rapidly produce antibodies if reinfected with the same antigen
role of antibodies
Precipitation:
makes soluble antigens insoluble so it’s easier for the phagocyte to engulf
Agglutination:
clumps cell bound antigens together for easier removal of pathogens
Neutralisation:
binds to and mask dangerous parts of pathogen
Inflammation:
trigger inflammatory response which makes it easier for phagocytes to move in infected tissue
Complement:
activate complement proteins which perforate pathogens cell membranes and causes cell lysis
vaccines
- contain weakened or dead pathogen, purified antigen, mRNA which codes for an antigen
- when we are injected the antibody production start but we do not get sick as it’s weakened pathogen & some b cells become memory cells
- in case of encounter with pathogen, because of memory cell, the symptoms aren’t as bad because it’s a secondary immune response (rapid)
smallpox
- edward jenner injected boy with cowpox because he noticed milkmaids who had cowpox didn’t get smallpox
- then injected boy with small pox and surely enough he didn’t get it/didn’t die because of it
- his techniques don’t comply with modern ethical guidelines (WHO has put in place guidelines)
- eradication was so successful because small pox wasn’t zoonotic (only affected humans) and immunity is long lasting
epidemiology
the study of the spread of disease, the causes of disease and distribution patterns in populations
useful for monitoring spread of disease and minimising/predicting harm cause by outbreak
histamine
- allergic reaction is when histamine is released by 2 main WBCs namely basophil and mast cells
- histamine causes dilation of small blood vessels which increases blood flow. it also attracts WBCs to infection site & increases permeability of blood vessels so that WBCs and antibodies can enter into tissues
- first stage of allergic reaction is sensitisation which is when a specific B-cell is first activated by an allergen. it then differentiates into plasma cells which secrete large quantity of an antibody called Immunoglobulin E (IgE) which attracts mast cells to which IgE binds
- then comes the actual allergic reaction which is causes when re-exposed to the same allergen. the IgE primes mast cells secrete large amounts of histamine which causes inflammation
symptoms: itching, rash, redness, anaphylaxis
treatment: epinephrine, antihistamine
monoclonal antibodies
- a mouse is injected with a specific antigen then it’s B cells are collected
- myeloma cells are collected from a different mouse
- B cells and myeloma cells fuse together forming hybridoma cells (which produce antibodies and are long lasting)
- the hybridoma cells are identified to see which ones produce the desired antibody
- those hybridoma cells are cultured where they divide and produce large quantities of the desired antibody
- can be used as a diagnostic tool
