Lecture 4 - Immunity Part 1 Flashcards

Question

What are B and T cells?

Answer 1

Both are Lymphocytes Second most abundant white blood cells Originate from the Bone Marrow B cell leave the bone marrow as mature cells T cells leave as immature cells and travel to the Thymus

Answer 2

T Cells leave the bone marrow as immature, and mature in the Thymus. T –Cells at the thymus will separate into 2 sub populations: T Helper Cells aka CD4+ Support B cell to produce Antibodies Cytotoxic T Cells aka CD8 + or Killer T Cells Act as Killer cells (bit like NK but more specific) These bind to antigen presenting cells with MHC Class 1

Answer 3

Cytotoxic T cells kill their targets by programming them to undergo apoptosis. The principal mechanism through which cytotoxic T cells act is by the calcium-dependent release of specialized lytic granules upon recognition of antigen on the surface of a target cell. Cytotoxic effector proteins that trigger apoptosis are contained in the granules of CD8 cytotoxic T cells. As well as killing the host cell, the apoptotic mechanism may also act directly on cytosolic pathogens. For example, the nucleases that are activated in apoptosis to destroy cellular DNA can also degrade viral DNA. Apoptosis is therefore preferable to necrosis as a means of killing infected cells; in necrosis, intact pathogens are released from the dead cell and these can continue to infect healthy cells, or can parasitize the macrophages that ingest them.

Answer 4

They are similar to macrohoages, but are specific, meaning they only attack one kind of intruder. They create antibodies during an immune response These Antibodies are Y- shaped proteins that are specific to each pathogen and can lock onto the surface of an invading cell and mark it for destruction by other immune cells.

Answer 5

Aka Immunoglobulins Large Y- Shaped Protein used by the immune system to identify & neutralize pathogens Antibodies comprise 20% of the plasma proteins Antibodies not only comprise regions of high diversity (antigen binding sites; FAB); they also have regions that are more consistent between molecules (constant regions; FC): the FC regions can have a variety of functions. Antibodies have: Specificity individually Diversity as a group

Answer 6

Complex macromolecules (either proteins, glycoproteins or carbohydrates) that can bind to a specific antibody or T cell receptor, thus triggering and immune response.

Answer 7

When a B cell finds a particle in the body that matches its unique receptor site, it attaches by its receptor site and digests it through a process similar to phagocytosis. It then displays the digested viral or bacterial pieces on its cell surface which attracts Helper T cells. If the Helper T cell also has a specific binding site that matches the digested bits on the B cell, then it knows that the digested particle is harmful! If it hadn’t already been alerted (and activated) by a macrophage of the same threat, it now becomes activated. The activated Helper T cell, in turn, activates the B cell, and this interaction causes the B cell to divide. After a few days, the young B cells will mature and differentiate into: plasma cells and memory B cells. Plasma cells use their machinery to produce antibodies. Memory B cells remain in the body and "remember" the proteins the infectious particle had. So in the future if it encounters the same particles with the same antigens then it can launch a quicker and stronger response.

Answer 8

recognise previously encountered pathogenic organisms and then rapidly multiply by a form of natural cloning to produce large amounts of antibody. More than 10 million varieties of antigenic site are possible. These help form our ‘memory” of previous infections, so if we encounter it again, our immune system will remember how to fight it off! How vaccines work! But, can also get us into trouble with autoimmune disorders & allergies

Answer 9

IgG, IgA, IgM, IgE and IgD Their exact function and location in the body are determined by their type. They act by signalling the presence of an invader to other cells, which will then attack it.

Answer 10

The main immunoglobulin in mucosal areas / secretions e.g. gut, respiratory tract and urogenital tract, saliva, tears & breast milk. small amounts are found in the blood. prevents colonization by pathogens It is able to survive in harsh conditions such as a the GI tract.

Answer 11

Functions mainly as an antigen receptor on B cells that have not been exposed to antigens (so helps with B cell maturation) It has been shown to activate basophils and mast cells to produce antimicrobial factors Exact functions remain unclear.

Answer 12

Involved in allergies! Binds to allergens triggers histamine release from mast cells and basophils, Also protects against parasitic worms. IgE's main function is immunity to parasites such as helminths IgE also has an essential role in type I hypersensitivity which manifests various allergic diseases such as: allergic asthma most types of sinusitis. allergic rhinitis food allergies specific types of chronic urticaria and atopic dermatitis. IgE also plays a pivotal role in responses to allergens, such as: anaphylactic drugs, bee stings, and antigen preparations used in desensitization immunotherapy.

Answer 13

Most common antibody found in circulation . provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to the fetus It is secreted in breast milk (alongside IgA) and provides immunity for the infant after birth before their own immune system develops.

Answer 14

Expressed on the surface of B cells (monomer) and in a secreted form (pentamer) with very high binding ability. Eliminates pathogens in the early stages of B cell-mediated immunity before there is sufficient IgG. IgM is responsible for agglutination (clumping) of erythrocytes during a blood transfusion, if the recipient receives blood that is not compatible with their own blood type

Answer 15

It is a type of granulocyte They play an important role in many inflammatory settings such as: Defence against parasitic infections play a role in allergic reactions. They are important in both the innate and adaptive response There are located between the boundaries of the tissues and external environment e.g. skin and blood vessels. They play a key part in the inflammatory response When they become activates, they release a wide variety of inflammatory mediators Histamine > Increase Vascular Permeability Cytokines > Promotes tissue inflammation Leukotrienes & Prostaglandins > Increase Vascular permeability

Answer 16

Is a small molecule which, when combined with a larger carrier such as a protein, can elicit the production of antibodies which bind specifically to it (in the free or combined state). In itself it can bind to an immunoglobulin, but will ONLY trigger an immune response if it is also bound to a carrier protein. They have a role in molecular biological applications when studying immunochemical reactions.