Introduction immunology - L3 Flashcards
Name examples of disturbed immunity/tolerance and of artificially induced immune responses.
- Disturbed immunity/tolerance: rejected transplant organ, allergy, autoimmunity.
- Artificially induced immune responses: vaccination, anti-tumor therapy
Describe characteristics of the innate and adaptive immune system.
- Innate immune system: fast but non-specific. Cells are already present. Cells involved: macrophages, dendritic cells, mast cells, NK cells, neutrophils, eosinophils, basophils, etc.
- Adaptive immune system: slow, but specific and memory. Need for lymphoid organs to produce these cells. Cells involved: B and T cells.
What is the difference between peripheral blood mononuclear cells and polymorphonuclear granulocytes?
- Peripheral blood mononuclear cells are B, T and NK cells.
- Polymorphonuclear granulocytes are neutrophils, eosinophils, and basophils.
Explain in short the functions of the following cells:
- Small lymphocytes
- Plasma cells
- Natural killer cells
- Neutrophils
- Eosinophils
- Basophils
- Dendritic cells
- Mast cells
- Monocytes
- Macrophages
- Small lymphocytes: production of anitbodies or cytotoxic and helper functions
- Plasma cells: fully differentiated form of B cells that secretes antibodies.
- Natural killer cells: kills cells infected with certain viruses.
- Neutrophils: phagocytosis and killing of microorganisms.
- Eosinophils: killing of antibody-coated parasites through relase of granule contents.
- Basophils: controlling immune responses to parasites.
- Dendritic cells: activation of T cells and initiation of adaptive immune responses.
- Mast cells: expulsion of parasites from body through release of granules containing histamine and other active agents.
- Monocytes: circulating precursor cell to macrophage.
- Macrophages: phagocytosis and killing of microorganisms. Activation of T cells and initiation of immune responses.
The immune system has three lines of defense against invasion by pathogens. Name these.
- Barriers such as skin, mucous, membranes and chemicals.
- Innate immune system, phagocytosis, complement system, interferon, inflammation, fever.
- Adaptive immune system, lymphocytes, antibodies.
Explain how inflammation is a result of the second line of defense of the immune system.
- When bacteria come into contact with tissue as a result of e.g. a wound, this activates resident effector cells to secrete cytokines.
- Vasodilation and increased vascular permeability allow fluid, protein, and inflammatory cells to leave the blood and enter the tissue.
- The infected tissue becomes inflamed, causing redness, heat, swelling, and pain.
What are cytokines and what are chemokines?
They are small soluble proteins secreted by cells (messengers).
* Cytokines: stimulate cell division and activation.
* Chemokines: attract cells/stimulate migration.
As already mentioned, the adaptive immune system requires lymphoid organs for the production of T- and B cells. For this, primary and secondary lymphoid organs exist. Explain the characteristics of these two types of lymphoid organs.
- Primary lymphoid organs: consists of the bone marrow for the production of naive B cells and the thymus for the production of naive T cells.
- Secondary lymphoid organs: consists of lymph nodes, spleen, and Peyer’s patches (small intestine) and filters lymph fluid/cells that drains from tissues. This is where lymphocytes are activated.
T cells consist of CD8+ T cells and CD4+ T cells. What is the difference between the two?
- CD8+: also called cytotoxic T cell, it release cytokines that kill infected cells.
- CD4+: also called T helper cells, help other immune cells in killing infected cells (e.g. activating plasma cells).
- Where are B cells produced?
- Do B cells recognize intact or processed antigens?
- Produced in the bone marrow
- Intact antigen recognition
- Where are T cells produced?
- Do T cells recognize intact or processed antigens?
- Produced in the thymus
- Recognition of processed antigens on antigen presenting cells
The innate immune system has several ways to detect and destroy pathogens. One of them is the complement system that consists of three ‘routes’ used to activate this system. Name these three routes.
- Alternative route, reacts to bacterial endotoxins.
- Lectin route, reacts to mannose binding lectin.
- Classical route, reacts to antigen-antibody reaction.
Describe the classical pathway of the complement system.
- An antigen-antibody reaction triggers this pathway.
- This activates the C1 complement protein, which cleaves another complement protein C4 into C4a and C4b.
- C1 binds with C4b to form C14B
- C14B cleaves C2 into C2a and C2b.
- C14b binds with C2a to form C14b2a (C3 convertase).
- C3 convertase cleaves C3 into C3a and C3b.
- C3b binds with C3 convertase to form C14b2a3b (C5 convertase)
- C5 convertase cleaves C5 into C5a and C5b.
- C5b binds with C6, C7, C8, and C9 to form C5b6789, known as the membrane attach complex (MAC)
Describe the alternative pathway of the complement system.
- A bacterial endotoxin (e.g. LPS) triggers this pathway.
- This result in hydrolysis of factor C3, forming factor C3b.
- Factor B binds with factor C3b.
- Factor B is then converted into Ba and Bb by factor D.
- Factor Bb binds with factor C3b to form factor C3bBb (i.e. C3 convertase).
- C3 convertase cleaves C3 into C3a and C3b.
- C3b binds with C3 convertase to form C14b2a3b (C5 convertase)
- C5 convertase cleaves C5 into C5a and C5b.
- C5b binds with C6, C7, C8, and C9 to form C5b6789, known as the membrane attach complex (MAC).
Describe the lectin pathway of the complement system.
- This pathway is initiated by recognition of the mannose or glucose present in some bacteria. Mannose is recognized by the protein mannose binding lectin (MBL).
- MBL activates mannose binding lectin associated serine protease (MASP).
- MASP activates C4 and C2 and cleaves it into C4a, C4b, C2a, and C2b.
- C4b binds to C2a and forms C4bC2a (i.e. C3 convertase).
- C3 convertase cleaves C3 into C3a and C3b.
- C3b binds with C3 convertase to form C14b2a3b (C5 convertase)
- C5 convertase cleaves C5 into C5a and C5b.
- C5b binds with C6, C7, C8, and C9 to form C5b6789, known as the membrane attach complex (MAC).
