Immunity Flashcards
What are phagocytes?
scavenger cells present in the body and blood which remove dead cells and pathogens
What are macrophages?
type of phagocyte found settled in organs (monocytes in blood), long-lived
What are neutrophils?
type of phagocyte and white blood cell which patrols body, released in large number during infections, short-lived
What is the mode of action of phagocytes?
macrophages split pathogens to display their antigens to lymphocytes, neutrophils do phagocytosis (chemotaxis, recognition and attachment, endocytosis, phagocytic vacuole, phagosome, killing and digestion)
Where do phagocytes originate?
bone marrow
What are B-lymphocytes?
a type of lymphocyte, which is a type of white blood cell, remain in blood cell until maturity, then spread through body, concentrated in lymph nodes and spleen
What is the mode of action of B-lymphocytes?
B-cells gain the ability to make one type of antibody as they mature, they divide to make a clone, antibodies remain in B-cell and form part of glycoprotein receptor, which can combine with a specific antigen, B-cells are activated during immune response, in which clonal selection and expansion happens, some activated B-cells become plasma cells, some become memory cells
What are T-lymphocytes?
a type of lymphocyte, which is a type of white blood cell, leave bone marrow and mature in thymus
What is the mode of action of T-lymphocytes?
T cell receptors are specific to one antigen, when activated, T cells go through clonal selection and expansion, helper T cells release cytokines that stimulate B cells to divide or macrophages to work, killer T cells look for invaded cells displaying foreign antigens and kill them by attaching and secreting toxic substances, memory helper and killer T cells are formed
What is the significance of increase in white blood cell counts?
an increase in neutrophils indicates a bacterial infection or the inflammation and death of tissue, an increase in lymphocytes indicates a viral infection or tuberculosis
What is leukaemia?
cancers of the stem cells in the bone marrow which produce neutrophils, macrophages, platelets, and lymphocytes
What is myeloid leukaemia?
cancer of the stem cells which produce neutrophils, macrophages, and platelets
What is lymphoid leukaemia?
cancer of the stem cells which produce lymphocytes
What is immune response?
a series of responses of the body involving lymphocytes and neutrophils to the detection of foreign antigens
What is an antigen?
a substance foreign to the body which stimulates an immune response
What is self and non-self?
self is any substance in the body not recognised as foreign by the immune system
What are memory cells?
activated B cells which remain in the body after the disposal of the invading antigen, they divide much faster during secondary response and allow long-term immunity
What is long-term immunity?
when the body has memory cells for a certain antigen, allowing faster and more efficient response the next time the antigen is encountered
What is an autoimmune disorder?
when the immune system attacks one or more self-antigens resulting in symptoms
What is myasthenia gravis?
a type of autoimmune disease in which the neuromuscular junctions between motor neurones and muscle cells, acetylcholine receptors on muscle cells have antibodies on them so nerve impulses are blocked, and sodium ion channels do not open, so muscles are not stimulated and eventually breakdown
What are some autoimmune disorders?
myasthenia gravis, rheumatoid arthritis, type 1 diabetes, multiple sclerosis, systemic lupus
What are the structural features of antibodies?
- globular glycoproteins
- 4 polypeptide chains
- two long/heavy
- two short, light
- held together by disulfide bonds
- variable region - two antigen bonding sites formed by light and heavy chains, amino acids make specific bonding shape
- hinge region
What are the functional features of antibodies?
- combine with viruses or toxins to prevent entry to cells
- attach to flagella of bacteria making them less active and easier for phagocytes to engulf
- multiple antigen binding sites cause agglutination preventing spread of bacteria
- punch holes in cell wall of bacteria causing lysis
- coat bacteria making it easier for phagocytes to ingest
- act as antitoxins
What are monoclonal antibodies?
identical antibodies secreted by a particular B cell clone made using the hybridoma method
What is the hybridoma method?
fusing plasma cells which produce a particular antibody with cancer cell, to produce a hybridoma cell, which divides indefinitely and produces antibodies
How are monoclonal antibodies used in the diagnosis of disease?
by injecting laboratory animals with the substance to be located, collecting plasma cells with antibody against substance, fusing with cancer cells to form hybridomas, making radioactively-labelled antibodies, introducing into patients blood, tracked with gamma ray camera
How are monoclonal antibodies used in the treatment of disease?
humanising antibodies by altering the genes that code for the heavy and light polypeptide chains of the antibodies from lab animals so they code for human amino acid sequences, and by changing the type and position of the sugar groups attached to the heavy chains to the human antibody arrangement
What are the types of immunity?
active, passive, natural, artificial
What is active immunity?
immunity gained when an antigen enters the body, an immune response occurs, and antibodies are produced
What is passive immunity?
immunity gained without an immune response
What is artificial immunity?
immunity gained artificially
What is natural immunity?
immunity gained by being infected, or by receiving antibodies from mother across placenta or through breast milk
What are some examples of each type of immunity?
- active natural - being infected
- active artificial - vaccination
- passive natural - placenta or breast milk
- passive artificial - injecting antibodies
What is vaccination?
a preparation containing antigens used to stimulate an immune response artificially
How can vaccination control disease?
by vaccinating large amounts of people at the same time to give herd immunity, which interrupts the transmission cycle so susceptible do not encounter the infectious agent
Why have vaccination progammes been able to eradicate smallpox?
- ring vaccination
- variola virus was stable
- live vaccine made of harmless strain
- cheap
- freeze dried for use in tropics
- easy to identify
- easy to administer (bifurcated needle)
- virus did not linger in body
- did not infect animals
- enthusiastic youth
Why have vaccination programs not been able to eradicate measles?
- poor response to vaccine by children who need boosters
- high birth rates and shifting population
- hard to trace contacts and follow up cases
- migrants and refugees form reservoirs
- highly infectious
- need high herd immunity (whole population)
Why have vaccination programs not been able to eradicate tuberculosis?
antigenic concealment - the vaccine is not very effective, as antibodies cannot cross cell surface membranes to reach m. tuberculosis, which infects host cells
Why have vaccination programs not been able to eradicate malaria?
antigenic variation - protoctists are eukaryotes with many genes and surface antigens, plasmodium has different antigens at each stage of life cycle
antigenic concealment - plasmodium enter liver and red blood cells
Why have vaccination programs not been able to eradicate cholera?
antigenic concealment - vibrio cholerae remains in the intestine beyond the reach of antibodies
What diseases can monoclonal antibodies diagnose?
blood clots in deep vein thrombosis, cancer cells, strain of virus or bacterium, blood typing before transfusion, tissue typing before transplant
What diseases can monoclonal antibodies treat?
breast cancer, melanoma, rheumatoid arthritis, leukaemia
