Immunology Flashcards
What are the causes of inflammation?
Necrosis/infarction/direct trauma
Infection (bacterial, viruses, fungi, protozoa, parasites)
Chemical or other physical agents, including radiotherapy
Autoimmune reactions, particularly hypersensitivity states.
What is a granuloma?
A granuloma is a tiny cluster of white blood cells and other tissue that can be found in the lungs, head, skin or other parts of the body in some people. Granulomas are not cancerous. They form as a reaction to infections, inflammation, irritants or foreign objects.
What is the major issue with chemotherapy?
As well as killing the fast-dividing cancer cells, it also damages fast dividing cells in the hair marrow and GI tract and the immune cells that govern the inflammatory response.
This means the patient experiences low immunity, hair falling out and diarrhoea.
What is peritonitis?
Peritonitis is an inflammation of the peritoneum, the tissue that lines the inner wall of the abdomen and covers and supports most of your abdominal organs. Peritonitis is usually caused by infection from bacteria or fungi.
Left untreated, peritonitis can rapidly spread into the blood (sepsis) and to other organs, resulting in multiple organ failure and death.
What is gastritis and what commonly causes it?
Gastritis is an inflammation, irritation, or erosion of the lining of the stomach. It can occur suddenly (acute) or gradually (chronic).
Gastritis can be caused by irritation due to excessive alcohol use, chronic vomiting, stress, or the use of certain medications such as aspirin or other anti-inflammatory drugs.
What is inflammation?
A reaction to injury or infection involving cells such as neutrophils and macrophages.
Inflammation is good in infection to start off healing process, but inflammation can also be bad in the context of auto-immunity and the fact that it causes pain.
ACUTE: sudden onset, short duration (usually neutrophil)
CHRONIC: slow onset or sequel, long duration (usually macrophage/leukocyte)
What are neutrophil polymorphs?
Short-lived cells first on the scene of acute inflammation.
Cytoplasmic granules full of enzymes that kill bacteria.
Usually die at the scene of inflammation, but release chemicals that attract other inflammatory cells such as macrophages.
What are macrophages?
Long-lived cells (weeks to months).
Phagocytic properties - ingest bacteria and debris.
May carry debris away and present antigen to lymphocytes.
Different names according to their location.
What are lymphocytes?
Long-lived cells (years).
Produce chemicals which attract other inflammatory cells.
Immunological memory for past infections and antigens.
Able to produce clones.
What happens to endothelial cells in inflammation?
Endothelial cells line capillary blood vessels in areas of inflammation. They become sticky so inflammatory cells adhere to them. They become porous to allow inflammatory cells to pass into tissues. They grow into areas of damage to form new capillary vessels.
What are fibroblasts?
Long-lived cells.
Form collagen in areas of chronic inflammation and repair.
Produce scars.
What is acute appendicitis?
Unknown precipitating factor.
Neutrophils appear, blood vessels dilate, inflammation of serosal surface occurs, pain felt.
Appendix is either surgically removed, inflammation resolves or appendix bursts with generalized peritonitis and possible death.
What happens after inflammation?
Usual result is resolution
Excessive exudate - discharge of pus
Excessive necrosis - repair and organisation leading to fibrosis
Persistent causal agent - chronic inflammation
What’s the difference between T and B cells?
T cells: mature in thymus, 80% lymphocytes, involved in cell-mediated immunity, identify viral antigens outside the infected cells.
B cells: mature in bone marrow, contain surface antigens, involved in humoral-mediated immunity, identifies surface antigens on viruses.
Which drugs treat inflammation?
Aspirin was one of the first anti-inflammatory drugs,
Ibuprofen is commmonly used.
Drugs that inhibit prostaglandin synthase (prostaglandins initiate inflammation).
Corticosteroids used to bind to DNA and upregulate inhibitors of inflammation and downregulate promoters of inflammation.
What is the difference between innate immunity and adaptive immunity?
Innate: instinctive, non-specific, does not depend on lymphocytes, present from birth.
Adaptive: specific, acquired/learned immunity, requires lymphocytes and involves antibodies
What is present in a blood sample?
TOP: Plasma - 90% water, electrolytes, proteins, lipids, sugars
MIDDLE: Buffy coat - made up of leukocytes
BOTTOM: Haemocrit - erythrocytes and platelets
What is serum?
Plasma without fibrinogen and other clotting factors
What are leukocytes?
White blood cells
Derived from multipotent haematopoietic stem cells(haemocytoblast) in the bone marrow. Different factors secreted to give different routes.
Polymorphonuclear leukocytes: neutrophil, eosinophils, basophils.
Mononuclear leukocytes: monocytes (macrophages), T cells and B cells.
What are mast cells?
Cells that are filled with basophil granules. Found in connective tissue and induce inflammation through the release of histamine and heparin.
What are natural killer cells?
Cells that circulate in blood and migrate into tissues. Able to kill tumour-cells or virus-infected cells.
What are dendritic cells?
Cells that present antigens on their surfaces, triggering adaptive immunity. Present in epithelial tissue.
What are the 3 soluble factors in the immune system?
Complement
Anitbodies
Cytokines and chemokines
What is the complement system?
Group of about 20 serum proteins secreted by the liver that need to be activated to be functional.
Have 3 modes of action: direct lysis, attraction of more leukocytes to the site of infection or coat invading organisms.
What are antibodies?
AKA Immunoglobulins
Can be soluble, secreted or bound to B cells as part of the B cell antigen receptor.
Bind specifically to antigens.
5 types: IgG, IgA, IgM, IgD and IgE
What are the different types of antibodies:
IgG: most predominant in human serum (70-75%). Present anywhere in the body.
IgM: pentamer with 10 binding sites. Accounts for 10% of Ig in serum. Mainly involved in the primary immune response (mIgM present as an antigen-specific receptor). Mainly found in blood as too big to cross endothelium.
IgA: usually a monomer. Accounts for 15% of serum. Predominant Ig in mucous secretions such as saliva, colostrum, milk, bronchiolar and genitourinary secretions.
IgD: transmembrane monomer present on mature B cells. Accounts for 1% of serum.
IgE: expressed by basophils and mast cells. Accounts for only 0.05% of serum. Binding the Ag triggers release of histamine in hypersensitivity reactions.
What are interferons?
Group of signalling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumour cells.
Induce a state of antiviral resistance in uninfected cells and limit the spread of viral infections.
IFNa and B produced by viral-infected cells. IFNy released by Th1 cells.
What are interleukins?
Group of cytokines that are produced by leukocytes to regulate immune response. Can be pro-inflammatory (IL-1) or anti-inflammatory (IL-10). Can cause cells to divide, differentiate and secrete factors.
What are colony stimulating factors?
Secreted glycoproteins that bind to receptor proteins on the surfaces of hemopoietic stem cells, thereby activating intracellular signaling pathways that can cause the cells to proliferate and differentiate into a specific kind of blood cell.
What are tumour necrosis factors?
Multifunctional cytokine produced by immune system cells. Act to promote the inflammatory process and can also induce necrosis in tumour cells (name’s sake).
What are chemokines?
Group of about 40 proteins that direct movement of leukocytes (and other cells) from the bloodstream into the tissues or lymph organs by binding to specific receptors on cells.
CXCL - mainly attract neutrophils
CCL - mainly attract monocytes, lymphocytes, eosinophils, basophils
CX3CL - mainly attract T lymphocytes and NK cells
XCL - mainly T lymphocytes
What 3 things make up innate immunity?
Physical and chemical barriers Phagocytic cells (neutrophils and macrophages) Blood proteins (complement system and acute phase)
What is inflammation?
A series of reactions that bring cells and molecules of the immune system to the site of infection or damage.
The hallmarks of inflammation include increased blood supply and vascular permeability and increased leukocytes transendothelial migration (extravasation).
Name some of the actions that may occur in the inflammatory response?
Initiates a response to:
Stop bleeding (coagulation)
Acute inflammation (leukocyte recruitment)
Kill pathogens
Neutralise toxins
Limit pathogen spread
Clear pathogens/dead cells (phagocytosis)
Proliferation of cells to repair damage
Remove blood clot (remodel extracellular material)
Re-establish normal structure/function of tissue
What are the two types of inflammation?
Acute: complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes and full regeneration of tissue.
Chronic: persistent, unresolved inflammation.
What are Toll-like receptors?
Type of pattern recognition receptor.
Recognise pathogen-associated molecular patterns expressed by microbes.
What are the 3 complement activation pathways?
Classical: Ab is bound to microbe
Alternative: complement binds to microbe
Lectin: activated by mannose binding lectin which binds to the microbe
