ICS - Immunology Flashcards
What is the difference between innate and adaptive immunity?
Innate = non-specific, instinctive, does not depend on lymphocytes Adaptive = specific, acquired, requires lymphocytes
What are haematopoietic pluripotent stem cells?
Haemocytoblasts = the stem cell that every blood cell in the body originates from
What is the most important cell type in innate immunity?
Neutrophils - phagocytosis (contain lysosomes that secrete toxic substances)
What is the role of monocytes and which type of immunity are they useful in?
Remove anything foreign (microbes) or dead
Innate (phagocytosis) and adaptive (Ag presentation)
What is the role of macrophages and which type of immunity are they useful in?
Remove foreign (microbes) and self (dead/tumour cells)
Innate and adaptive
Phagocytosis and Ag presentation to T-cells
What is the role of eosinophils and why are they needed in the immune system?
Parasitic infections and allergic reactions
Activates neutrophils, induces histamine release from mast cells and provokes bronchospasm
What is the role of basophils and why are they needed in the immune system?
Parasitic infections and allergic reactions
Binding of IgE to receptor causes de-granulation releasing histamine
Very similar to mast cells
What is the role of mast cells and why are they needed in the immune system?
Allergic reactions
Binding of IgE to receptor causes de-granulation releasing histamine
Only in tissues (precursor in blood)
What is the role of T-lymphocytes and which type of immunity are they useful in?
Adaptive immunity
Recognise peptide Ag displayed presenting cells (APC)
4 main types: T helper 1, T helper 2, Cytotoxic T cell, T regulator
What is the role of B-lymphocytes and which type of immunity are they useful in?
Adaptive immunity
Recognise peptide Ag displayed presenting cells (APC)
What is the role of natural killer cells?
They recognise virus infected/tumour cells and kill by apoptosis
What is the mode of action of complement?
Direct lysis
Attract more leukocytes to site of infection
Coat invading organisms
What is the role of antibodies?
Hallmark of adaptive immunity - they bind specifically to antigen (Ag)
Immunoglobulins - soluble
What are the 5 classes of immunoglobulins?
IgG - crosses placenta
IgA - predominant in mucous secretions such as saliva, milk and bronchiolar secretions
IgM - found in blood, primary response
IgD - transmembrane monomeric form is present on mature B cells
IgE - associated with allergic response (basophils/mast cells express IgE-specific receptors, binding triggers release of histamine)
Define antibody (Ab)
Protein produced in response to an antigen. Can only bind with antigen that induced its formation (specificity)
Define antigen (Ag)
A molecular that reacts with preformed antibody and specific receptors on T and B cells
Define epitope
The part of the antigen that binds to the antibody/ receptor binding site
Define affinity
Measure of binding strength between an epitope and an antibody binding site
Define cytokine
Proteins secreted by immune and non-immune cells. Substances produced by one cell that influence the behaviour of another
What is the role of interferons?
Induce a state of antiviral resistance in uninfected cells and limit the spread of viral infection
What is the role of interleukins?
Can cause cells to divide, to differentiate and to secrete factors
What is the role of colon stimulating factors (CSF)?
Involved in directing the division and differentiation on bone marrow stem cells
What is the role of tumour necrosis factors?
Mediate inflammation and cytotoxic reactions
What is the role of Chemokines?
They attract leukocytes to sites of infection/inflammation by binding to specific receptors on cells
Give 3 examples of anatomical barriers
Skin
Sebum (skin secretions)
Intact skin (prevents penetration)
Give 3 examples of mucous membranes (physical barriers)
Saliva
Mucous secretions
Low pH and commensals of vagina
Give 3 examples of physiological barriers
Temperature
pH
Gastric acidity
Define inflammation
A series of reactions that bring cells and molecular of the immune system to sites of infection or damage
What are the 3 hallmarks of inflammation?
Increased blood supply
Increased vascular permeability
Increased leukocytes trans-endothelial migration ‘extravasation’
What is the difference between acute and chronic inflammation?
Acute = complete elimination of a pathogen followed by resolution of damages, disappearances of leukocytes and full regeneration of tissue
Chronic - persistent, un-resolved
What are the 6 stages of phagocytosis?
Binding Engulfment Phagosome formation Lysosome fusion (phagolysosome) Membrane disruption Antigen presentation/ secretion
What is the role of major histocompatibility complexes (MHC)?
Display peptide from self/non-self proteins on the cell surface - invasion alert
MHC I - glycoproteins on all nucleated cells
MHC II - glycoproteins only on APC
MHC III - code for secreted proteins
What is the role of secreted and circulating pattern recognition receptors?
Lectins and collectins activate complement and improve phagocytosis
What is the role of cell-associated pattern recognition receptors?
Present on the cell membrane and recognise a broad range of molecular patterns
Toll-like receptors (TLRs) are the main ones
What are the 3 types of vaccines used?
Whole killed, toxoids, live attenuated
Define passive immunity
A short-term immunity which results from the introduction of antibodies from another person or animal
Define vaccine
Antigenic substance prepared from the causative agent of a disease
Give 3 reasons a vaccine may not be able to be produced for a specific pathogen
Pathogen is too hard to grow
Killed pathogen is not protective
Impossible to obtain attenuated and suitably immunogenic strain
What are the 5 stages of vaccination?
- Engage the innate immune system
- Danger signals that activate the immune system, triggers such as molecular fingerprints of infection - PAMPs
- Engage TLR receptors
- Activate specialist APC
- Engage the adaptive immune system
Give 4 hallmarks of cancer
Evade apoptosis
Limitless replication potential
Invade tissues
Escape immune surveillance
What is cancer immune-surveillance?
The immune system can recognise and destroy nascent transformed cells, normal control
What is cancer immunoediting?
The immune system can kill and also induce changes in the tumour resulting in tumour escape and recurrence
Give 3 examples of antigen-presenting cells
Macrophages, dendritic cells, B cells
What type of white blood cell is measured for HIV diagnosis and what level indicates AIDS?
CD4+ count, <200
