Immunology 1 Flashcards
What areas of medicine can progress in our of understanding of immunology?
Infectious disease
Cancer
Autoimmune diseases
And TRANSPLANTATION!
What type of revolutionary treatment changed the face of medicine in the late 1940’s-1960’s? And what diseases have they nearly eradicated?
Vaccination.
Measles, Polio and Diptheria
What are the mechanical, chemical and microbiological barriers of the skin, gastrointestinal tract, respiratory tract, urogenital tract and eyes?
Skin:
Mech- flow of fluid, perspiration and shedding of skin
Chemical- The Sebum, (fatty acids, lysozyme lactic acid)
Microbio- Flora of the skin
Gastro:
Mech- flow of fluid, mucus, food and saliva
Chem - acidity and enzymes I.e. Proteases
Micro- flora of gut
Respiratory tract:
Mech- flow of fluid and mucus (by Cillia) and air flow
Chem- lysozyme in nasal secretions
Microbio- flora of the respiratory tract
Urogenital tract:
Mech- flow of fluid, mucus, urine, sperm
Chem- acidity in vaginal secretions, spermine and zinc in sperm
Microbio- flora of UT
Eyes:
Mech- flow of fluid, tears
Chem- lysozyme in tears
Microbio- flora of eyes
Define innate immunity
Cells and components of the immune system which act without prior exposure to pathogens
Define complement
Inactive circulating serum proteins that act on pathogen cell membranes. When activated an amplified cascade effect can cause proteolytic enzymes to induce inflammation and cytotoxicity etc.
Describe the 4 basic steps of Opsonisation. (Of the complement system)
- Bacterial cell surface promotes complement cleavage and activation
- One complement fragment binds Covalently to bacterium, other ATTRACTS an EFFECTOR cell (e.g. Phagocyte)
- The complement receptor on the effector cells binds to complement fragment bound on bacterium
- Effector cell engulfs bacterium, kills it and breaks it down in the phagosome
What are the first three steps of complement defined to be and what is the last?
1-3: pathogen recognition mechanisms
4: effector mechanism
Define adaptive immunity!
Expansion of a population of cell with receptors for a particular infectious agent with exposure beforehand (normally a features of ‘higher’ organisms)
Define antigen!
Any molecule that stimulates an immune response, can be a protein or a lipid/glycolipid. MUST have a defined STRUCTURE and be FOREIGN
At what areas do most infections occur?
Across mucosal surfaces. YUM!
What type of bacteria does the lysozyme of mucosal surfaces break down? Gram negative , or gram positive?
Gram positive
Outline the basics of inflammation!
- Break in skin (wound) allows entry of bacteria into skin tissue, alerting nearby (resident) effector cells to express cytokines
- Vasodilation and increased VASCULAR permeability allow flow of fluid, protein (thrombin etc) and INFLAMMATORY CELLS from the blood into the skin tissue
- Inflammation occurs causing, swelling, heat, redness and pain
Compare the recognition mechanisms of innate and adaptive immunity with the following four criteria (time of response, type of response I.e. Fixed or variable, specificity and performance during response)
And give ONE common feature of both
Time: innate= hours (fast) adaptive= days/weeks (slow)
Type: innate = fixed . Adaptive= variable
Specificity: innate= limited number of specificities, adaptive= numerous highly selective specificities
Performance: I= constant, A= improves during response
ONE similarity is that they have similar mechanisms of pathogen destruction
What is the name of lymphatic cells that give rise to huge number of different lymphocytes during development ? What happens to these lymphocytes?
Progenitor cells.
Once infection occurs, lymphocyte that has correct receptor for antigen recognition is selected for proliferation upon which the infection is stifled
What is haematopoiesis?
The formation of blood cellular components.
What is interesting about haematopoiesis during the stages of the human life cycle?
It occurs in different organs. Yolk sac in zygote, liver and spline in feutus and bone marrow in children to adults
What do transcription factors do to haematopoiesis?
The specify the lineage of lymphoid differentiation
What affects the expression of transcription factors?
Cytokines!
What are the three most abundant immune cells (leukocytes) in the blood and what are their half lives? ⏳
1st. Neutrophil (40-70%) 6-12 hours
2nd. Lymphocyte (e.g. B cells) 20-50% 7-20 days (but memory lymphocytes can survive for years/lifetime
3rd. Eosinophil (1-6%) 30 mins
What is the process of optimisation? ⏳⏰⌚️
Coating of pathogen/bacterium surface with tags (complement or antibodies) that increase the likelihood of uptake (phagocytosis)
What are some of the structural features of a macrophage?
- phagosome
- lysosome
- phagolysosome
- pseudopodia (POoh DIA)
What role do Macrophages play in immunity?
Phagocytosis and killing of microorganisms and Stimulation of inflammation.
How do macrophages induce inflammation?
Component of Bacteria binds to SIGNALLING receptor of macrophage, stimulates the expression and release of inflammatory cytokines.
What percentage of deaths worldwide is attributed to infections?
10%
Is adaptive immunity exclusive to vertebrates, true of false?
True!
What is the medical term for when the immune system cannot mount a sufficient defence? And give two examples.
Immune deficiency.
- Human immunodeficiency Virus (HIV)
- SCID ?
What is the term when the immune system beignets to target and attack the host? And give one example.
Autoimmunity, example is Diabetes type 1
Define serum.
The non-cellular liquid fraction of blood after coagulation (without clotting factors)
Define Immunoglobulin.
A serum fraction that (gamma globulin) that has antitoxin, precipitin (precipitation In a tin) and agglutin (a glued tin).
What is the difference between an immunoglobulin and an antibody?
An immunoglobulin can come in two forms. One is membrane bound called surface Immunoglobulin and the other is secreted and is termed secreted immunoglobulin (aka antibody) (Y)
Define an Epitope.
the molecular sidechain of an antigen that each antibody attaches to; there can be many epitopes on a single antigen
Name two previous theories of immunology and outline them.
Also what is the current and most likely nature of immunology, give the name and details
- The instructional theory: antigens made antibodies fold around them in a specific way. This is false
- The selection theory: the body makes every possible chemical side chain on antibodies and when the antigen arrives it matches it’s epitope to the correct antibody side chains.
The current theory: monoclonal selection: which states that an individual lymphocyte (specifically, a B cell) expresses receptors specific to the distinct antigen, determined before the antibody ever encounters the antigen. Binding of Ag to a cell activates the cell, causing a proliferation of clone daughter cells. ????—> ????
What are four common mechanisms and components of the innate IS?
1.Phagocytic cells (macrophages, neutrophils; more generally, antigen-presenting cells (APCs)) 2. Barriers (e.g. skin) 3. Antimicrobial compounds 4. Inflammation
Describe one vital link between the innate immune response and the adaptive immune response? (Clue= APC’s)
APC’s engulf, digest and present epitopes of a particular antigen on their surface to B cells and T-cells of the immune system (of the adaptive IS), in this respect they localise the presentation of antigen!
Name three APCs.
- Tissue macrophages
- Monocytes within the blood
- Neutrophils
What pH does sebum lower skin to?
3.5
What is lysozyme?
Lysozyme–hydrolytic enzyme in tears and mucous; cleaves
peptidoglycan in bacterial cell walls
What is interferon?
Released by virus-infected cells that bind to nearby cell surfaces in a Paracrine fashion that arouses a general antiviral state.
What are the four main roles of the complement system? Briefly outline each.
Opsonisation: enhancing the likelihood of phagocytosis of an antigen
Chemotaxis: attracting macrophages and neutrophils
Cell lysis: rupturing the cell membrane of foreign cells
Agglutination: clustering and binding of pathogens together
What are leukocytes? (? hint: WBC)
WHITE BLOOD CELLS
Name the three myriad cell types that are derived from monocytes.
Dendritic cells
Macrophages
Mast cells
Name the three granulocyte cell types?
Neutrophils
Basophils
Eosinophils
What is included in the lymphoid cell lineage
Plasma cells (B cells)
Effector T cells
NK cells
What % of lymphocytes lie within the blood?
Less than 1%