11.1 Antibody production and vaccination Flashcards
What is referred to as an antigen?
Any foreign molecule that can trigger an immune response
What are antigens recognized by?
- Lymphocytes which bind to and detect the characteristic shape of an exposed portion (epitode)
What do lymphocytes do when they detect an antigen?
- Lymphocutes trigger antibody production (adaptive immunity) which specifically bind to epitopes via complementary paratopes
What are some antigenic determinants?
- Surface markers present on foreign bodies in the blood and tissues - including bacterial, fungal, viral and parasitic markers
- The self markers of cells from a different organism (this is why transplantation often results in graft rejection)
- Even proteins from food may be rejected unless they are first broen down into component parts by the digestive system
What is MHC? What is the opposite?
A self marker that lebels the body’s cells as a ‘friend’ and are tolerated by the immune system
An antigen is non self and is recognised as foreign by the immune system
Where are self markers (MHC class I) present on?
On surfaces of all nucleated body cells and identify the cell as part of the organism
* Different organisms have distinct self markers which prevent transplantation of tissues (unless a very close genetic match)
Why do red blood cells not possess the same distinctive and unique self markers as all other body cells?
Because they are not nucleated
* This means that red blood cells can be transferred between individuals without automatically causing immune rejection
What do red blood cells possess that limit the capacity for transfusion?
- Possess basic antigenic markers
- May possess surface glycoproteins (A and B antigens) either independently (A or B) or in combinatino (AB)
- Alternatively, red blood cells may possess neither surface glycoprotein (denoted as O)
In what ways if blood transfussion limited?
- AB blood groups can only recieve blood from any other type (as they already possess both antigenic variants on their cells)
- A blood groups cannot recieve B blood or AB blood (as the B isoantigen is foreign and will stimulate antibody production)
- B blood groups cannot receive A blood or AB blood (as the A isoantigen is foreign and will stimulate antibody producition)
- O blood groups can only recieive transfusions from other O blood donor (both antigenic variants are foreign)
What reaults in positive or negative blood groups?
An additional glycoprotein (Rhesus factor) is either present or absent, resulting in positive or negative blood groups
What results in positive or negative blood groups?
An additional glycoprotein (Rhesus factor) is either present or absent, resulting in positive or negative blood groups
What are the 2 most important antigen systems in blood transfusions?
The ABO blood group and the Rhesus (Rh) blood group are the two most important antigen systems in blood transfusion as mismatches between donor and recipient can lead to an immune response
What are the 2 most important antigen systems in blood transfusions?
The ABO blood group and the Rhesus (Rh) blood group are the two most important antigen systems in blood transfusion as mismatches between donor and recipient can lead to an immune response
What basic antigen sequence do all three alleles of the A, B, and O phenotypes have?
Antigen H
* Antigen H is modified by the addition of an additional molecule
* If the additional molecule is galacose, antigen B results etc.
What happens when a recippient is given a transfusion involving the wrong type of blood?
Agglutination followed by hemolysis where red blood cells are destroyed and blood may coagulate in the vessels
What does mixing the wrong type of blood with its anti A+B serum produce?
Red dots that are produced from agglutination
What is a pathogen?
An agent that causes disease - either a microorganism (bacteria, protist, fungi or parasite), virus or prion
* Are generally species-specific in that their capacity to cause disease (pathogenesis) is limited to a particular species (i.e. polio specifically affect human hosts)
What is a disease and illness?
- A disease is any condition that disturbs the normal functioning of the body (i.e. the body can no longer maintain homeostasis)
- An illness is a deterioration in the normal state of health of an organism (a disease may cause an illness)
What are zoonotic diseases?
Diseases from animals that can be transmitted to humans are called zoonotic diseases (or zoonoses) because certain pathogens may cross the species barrier and be able to infect and cause disease in a range of hosts.
e.g. rabies
What is the name of the pathogen that can cross a species barrier?
A zoonosis
What are the ways in which infectious diseases can be transmitted?
- Direct contact
- Exchange of fluids - sex, beastfeeding
- Contamination - food
- Airborne - transferred in the air
- Vectors - intermediary organisms that transfer pathogens without developing disease symptoms themselves
What is the name of the pathogen that can cross a species barrier?
A zoonosis
What is the major factor contributing to the increased appearance of zoonotic diseases?
Growth of contact between **animals and humans by such means as humans living in close contact with livestock or disruption of habitats.**
What does the body respond with when challenged by a foreign pathogen?
Respond with both a non-specific and a specific immune reaction
What are non-specific immune cells called and what do they do?
- Non-specific immune cells called macrophages will engulf pathogens non-selectively and break them down internally
- A proportion of macrophages (dendritic cells) will present the antigenic fragments of the pathogen to specific lymphocytes
How is the body able to recognize each single, specific antigen?
The body contained millions of different T lymphocytes and B lymphocytes that can recognize each
What activates B lymphocytes in mammals?
T lymphocytes
What do macrophages do with pathogens and their antigens?
- Pathogens are ingested by macrophages
- Antigens are displayed in the plasma membrane of macrophages
- Lymphocytes called helper T cells bind to antigens being displayed because they have an antibody-like receptor protein in their plasma membranes
- Helper T cells bind and are activated by the macrophage
- The activated helper T cells then bind to lymphocytes called B cells
- Selected B cells are activated by bindings to the helper T cell
- Release a signally protein after binding
Pathogens are ingested by macrophages, and antigens from them are displayed in the plasma membrane of the macrophages.Lymphocytes called helper T cells each have an antibody-like receptor protein in their plasma membranes, which can biind to antigens displayed by macrophages. Of the many types of helper T cells, only a few have receptor proteins that fit the antigen. These helper T cells bind and are activated by the macrophages.
The activated helper T cells then bind to lymphocytes called B cells. Again, only B cells that have a receptor protein to which the antigen binds are selected and undergo the binding process. The helper T cell activates the selected B cells, both by means of the binding and by release of a signally protein.
What is the overall process of how clones of a specific antibody is made and how does it provide long-term immunity?
- Antigenic fragments are presented to specifc helpter T lymphocytes that, when activated, release cytokines
- The cytokines stimulate a specific B cell that produces antibodies to the antigen to divide and form clones (clonal selection)
- Most of the clones will develop into short-lived plasma cells that produce large quantities of specific antibody
- A small proportion of clones will differentiate into long-lived memory cells that funciton to provide long-term immunity