immunology Flashcards
what are the two lines of defences in the immune system?
innate immunity
adaptive/ acquired immunity
what is 1st line barrier to immune system?
intact skin
mucous membranes
normal microbiota
what is 2nd line defence?
- Phagocytes
- Inflammation
- Fever
- Secretions
what is 3rd line defence?
- Specialised Lymphocytes
- T and B cells
- Antibodies
slower
but this one has memory capacity
what are the types of immune cells and their roles?
B- cell- antibody production
t-cell- destruction of pathogens
dendritic cell- present antigens to immune system
macrophage- antigen presentation and ingestion/destruction. also secrete cytokines
neutrophil- contain lysozyme- opsonized microbes
how does the immune system recognise triggers?
Innate immunity relies on a limited range of immune cells to detect and
respond rapidly to a wide range of pathogens that share common
molecular patterns not native to the human body
* Pathogen Associated Molecular Patterns (PAMPs).
what are PAMPs?
– Bacterial cell wall components such as lipopolysaccharides (LPS)
– Double-stranded ribonucleic acid (dsRNA) produced during viral
infection
what are DAMPs?
damage associated molecular patterns
what is difference in PAMPs and DAMPS?
- Pathogen Associated Molecular Patterns (PAMPs) are common to MANY
pathogens/microbes - Damage Associated Molecular Patterns (DAMPs) associated with tissue
damage also activate innate immunity
what is a hapten/ antigen/ epitope?
– Hapten = any small molecule that can elicit an immune response
– Antigen = a molecule that stimulates immune response and reacts
with antibodies
– Epitope = a small portion of amino acid on the surface of the antigen
what do PPRs activate?
destruction- phagocytes
what are the major cells of the adaptive immune system?
– Antigen Presenting Cells (APCs)
– Antigen-specific T cells
– B cells which differentiate into plasma cells to produce antibodies
when do the immune cells undergo expansion?
- First response to lymphocyte activation
- System of regulation where only cells which recognise that infection are needed
and therefore driven to undergo mitosis
what drives immune cell expansion?
- Antigen-driven, antigen-specific proliferation
(daughter cells recognise same target)
what are the characteristics of T cells?
- Develop in bone marrow but mature
in Thymus - Most common lymphocyte
- Three broad-types
– Helper CD4+ (cytokine factories)
– Cytotoxic CD8+ (cytotoxic)
– Regulatory (anti-inflammatory)
what are the characteristics of B cells?
Develop in Bone marrow
* Produce antibodies
* Binds to target antigen on pathogen
– Neutralising (e.g. stopping
function)
– Labelling (e.g. for phagocytosis)
– Killing (e.g. binding to
complement proteins in plasma)
* 5 types; IgM, IgG, IgE, IgA, IgD
what do CTL release?
L releases cytotoxic granules
– Granzymes A, B, H, K, M
– Serine proteases - Cleave proteins
– Granzyme B cleaves proteins
AFTER Aspartate residue
– Activates caspases in the target
what are cytotoxic t cells?
- Known as Cell mediated immunity
- CytoToxicLymphocyte (CTL) docks with
infected cell
what does the immune response with T helper and B cells also known as?
Known as Humoral immunity
what do B cells generate?
antibodies
which are effective against individual strain/species/ variant
what do antibodies cause?
- ‘Opsonisation’ coating of foreign targets
- Improves phagocytosis by neutrophils and
macrophages - Neutralisation -Blocking pathogen/toxins from binding to targets
- Degranulation of cells and inflammation
how do antibodies aid phagocytosis?
- Antibody bound to Pathogen docks with phagocytes and Killer cells
- Fc portion binds to FC Receptor on phagocyte
what immune system has memory?
adaptive
