Topic 11.1 - Antibody production and vaccines Flashcards
Antigens
Every organism has unique molecules on the surface of their cells. Any foreign molecule that can trigger an immune response -> antigen
Most common antigens are proteins and large polysaccharides.
Influenza virus has the hemagglutinin protein that binds to the surface of host cells.
Antigens in blood transfusion
Antigens on red blood cell surface stimulate antibody production in a person with a different blood group.
ABO and Rh blood group are important antigen systems.
(Look at sheet/ page 466 showing additional molecules that make up antigens)
Wrong transfused blood
Since blood contains the antibodies for blood that is not the group that the body has (for example blood type O has antigens against A and B antigens), any incorrect blood groups will be destroyed.
The antibodies (IgM) are pentamer: they attach to 5 blood cells at once. These antibodies then cause agglutination - where blood cells clump up together. This could block blood vessels and be fatal.
Immunoglobulins
igM igG igA igD igE
Specific immune response
Macrophages consume the pathogen and display the antigens of the pathogen on its surface (APC - antigen-presenting cell).
T helper cells then try to attach to the antigen and the T helper cell with the correct complementary antigen bind to the macrophage and becomes activated.
This activated T helper cell then attaches to the complementary B lymphocyte which is then activated to become either a memory cell or plasma cell, with plasma cells releasing antibodies against the pathogen.
Plasma cells
Plasma cells are produced by B lymphocytes becoming activated and since they manufacture, modify, and transport proteins, they have many rERs.
They also have dark staining because of large numbers of unexpressed genes. There are large numbers of unexpressed genes as these cells only and repeatedly produce the same type of protein.
Plasma cell creation is called clonal selection because there are many clones of the same type of cell that produces the same specific antibody.
Memory cell formation
After the infection is finished, plasma cells slowly disappear and are lost. Despite this, being infected by that pathogen rarely occurs as memory cells are present.
During plasma cell formation, a small number of memory cells are formed. These cells remain in the body for a very long time and remain inactive until the pathogen with their complementary antigen is present.
If the pathogen enters the body again, the memory cells reactivate and the antibodies to destroy the pathogen are produced quickly. This is how immunity works.
Role of antibodies
Antibodies aid in the destruction of pathogens in many ways: Opsonisation, neutralisation, activation of complement, and agglutination.
Opsonisation
Pathogen becomes more recognisable to phagocytes which can then consume the pathogen quicker and easier.
Neutralisation
Antibodies can bind to viruses or toxins to prevent viruses from docking to host cells or toxins from attacking susceptible cells.
Activation of complement
Complement system is a collection of proteins that lead to the perforation of membranes. The complement cascade is triggered by proteins which create a membrane attack complex. A membrane pore is opened and water and ions flood into the cell, causing it to lyse.
Agglutination
Pathogens are clumped together (usually by IgM antibodies as they are pentamer) and prevented from attacking cells and are also made easier to be consumed by phagocytes.
Immunity
Caused by having memory cells against that pathogen. First immune response -> takes a while for the pathogen to be destroyed and antibodies take a while to be produced.
Secondary immune response -> Pathogen destroyed quickly and antibodies produced extremely rapidly, also more produced than in primary response.
Types of immunities -> active and passive
Active immunity
Caused by being creating your own memory cells. Example is being infected by the pathogen and creating your own defence and memory cells.
Passive immunity
Caused by receiving the memory cells from another source. Example is receiving memory cells through breast milk.
Inflammation
Caused by phagocytes moving towards an infected area and causing swelling.
Vaccines
Put an attenuated version of the pathogen in the body so that immunity can be easy and relatively harmless.
Smallpox
First infectious disease eradicated by vaccines.
Zoonoses
Infectious diseases that can cross the species barrier. Examples include fever, bird flu, Lyme, and West Nile.
Histamines
Produced after basophils release it after detecting allergic substances or by mast cells after detecting infection.
Causes dilation of vessels in the infected areas, supplying more of the immune response substances, triggering both specific and non-specific responses. Also causes allergy symptoms and possibly even anaphylaxis.
Hybridoma cells
Result of a fusion cell with an antibody-producing cell.
Antigen injected into mouse -> immune system creates b lymphocytes -> spleen removed and lymphocytes obtained -> lymphocytes fused with myeloma (cancer) cells -> These cells are hybridoma cells.
Hybridoma cells can be used to mass-produce a particular antibody.
Monoclonal antibodies
Antibodies formed by hybridoma cells.
Diverse b cells in the spleen - leads to many types of hybridoma cells being produced. After the correct hybridoma cell has been identified, putting the hybridoma cell in a fermenter can cause the mass-production of the monoclonal antibodies.
Used for both treatment and diagnosis: HIV, Malaria, and pregnancy tests for example.
Monoclonal antibodies in pregnancy tests
During pregnancy, hCG (human chorionic gonadotrophin) is produced and by using monoclonal antibodies for hCG, pregnancy can be detected.
Urine interacts with the test kit -> if hCG is present, it binds to hCG antibodies that are bound to a dye -> the fluid moves down further where there are immobilised hCG antibodies and they react with any hCG, removing the dye and making a stain -> fluid moves down to the bottom of the kit and leftover antibodies react with immobilised antibodies, producing dye.
If hCG is not present, it doesn’t bind at the first dye producing site. However, the last site is a control site and should always produce dye to show that the test is working.
Neutrophils
Normal value blood %: 54-62
Function: Kill and digest bacteria and fungi, first step in immune response.
Elevated levels may mean: bacterial infections, stress.
