Immunodeficiency

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  • Created by: hadar
  • Created on: 27-02-18 08:58
How does the immune system protect from infection?
1)recognise pathogens 2)mount an immune response which requires cell-cell communication 3)clears the pathogen 4)self-regulates
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Describe innate immunity
General, not antigen specific but can recognise broad classes e.g. bacteria Rapid speed of onset Does not alter on repeated exposure No memory
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Describe adaptive immunity
antigen specific Slower response, but more potent Subsequent exposure- more effective response memory
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Define immunodeficiency
Clinical situations where the immune system is not effective enough to protect the body against infection
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What is primary and secondary immunodeficiency?
primary= Inherent defect within the immune system- usually genetic. secondary= Immune system affected due to external causes
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Give 5 examples of secondary causes of immunodeficiency
1)break down in physical barriers e.g. CF 2)protein loss 3)malignancy 4)drugs 5)infection -HIV/TB
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What drugs can cause secondary immunodeficiency?
Steroids, DMARDS, Rituximab, anti-convultants, myelosuppressive
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What are pathogen recognition receptors (PRR's)?
recognise conserved pathogen associated molecular patterns (PAMPs) which are unique to each pathogen- used to detect pathogens
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Give examples of PRRs and PAMPs pairs
1)TLR4-lipopolysacchharides 2)TLR5-flagellin 3)TLR3-viral RNA (defects lead to recurrent HSV encephalitis)
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What happens once a PRR binds and recognised PAMP?
Cascade of events involving various molecules intracellularly production of inflammatory cytokines MyD88 and IRAK4 are involved in this cascade
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What is the clinical presentation of IRAK4 deficiency?
Recurrent bacterial infection, especially streptococcus and staphylococcus Pneumonia, meningitis, arthritis Poor inflammatory response Susceptibility to infection decreases with age
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What is the treatment for IRAK4 deficiency?
prophylactic antibiotics, iv immunoglobulin if severe
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What is the clinical presentation of chronic granulomatous disease?
Recurrent abscesses: lung, liver, bone, skin, gut Unusual organisms e.g. Staphylococcus, Klebsiella, Serretia, Aspergillus, Fungi
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What is the pathophysiology of chronic granulomatous disease?
Defect in the NADPH complex- formed of several proteins including gp91phox (coded by the X chromosome)- this results in the oxide not being able to be reduced to form the superoxide required for enzymes of the phagocyte cell.
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What is the treatment for chronic granulomatous disease?
haemopoeitic stem cell transplant, antibiotics
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What test can be done to diagnose chronic granulomatous disease?
Tests rely on REDUCTION (gain of electron) Measure Dihydrorhodamine reduction using flow cytometry-- Nitro blue tetrazolium dye reduction- healthy neutrophils should go purple
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What is the function of complement?
1)Cell lysis (kill invading bacterium) 2)Control of inflammation 3)Stimulate phagocytosis
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Outline the 3 complement pathways and what stimulates each one
1)classical 2)lectin 3)alternative
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In what diseases is C2, C4 deficiency seen?
SLE, infections, myositis
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In what disease is C5-C9 (form membrane attack complex) deficiency seen?
Presents with repeated episodes of BACTERIAL meningitis Particularly Neisseria meningitis
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What results in binding of antibody to antigen?
1)neutralisation 2)agglutination of microbes 3)precipitation of dissolved antigens 4)activation of complement system
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What is X-linked agammaglobulinaemia?
Defect in Bruton’s Tryrosine kinase Needed for B cell signalling and B cell maturation B cell maturation not completed in the bone marrow
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What is the presentation of X-linked agammaglobulinaemia?
Presented before the age of 5 3 hospital admissions from pneumonia Recurrent chest infections in between Sinusitis-- No B cells, normal T cells No IgG, IgA, IgM CT: bronchial thickening, evidence of recent pneumonia-- mother passes away young
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List 4 B cell defect disorders
1)CVID 2)IgA deficiency 3)X linked hyper IgM syndrome 4)transient hypogammaglobulinaemia of infancy
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What is the consequence of defects in B cells?
loss of antibody secretion. Usually leads to recurrent bacterial infection with pyogenic organisms. Treat with antibiotics then i.v IgG for life. Most are very serious
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What drugs can cause secondary antibody deficiency?
Rituximab, methotrexate, azathioprine, ciclosporin, prednisolone, cyclophosphamide….
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What treatment is given for antibody deficiency treatment?
1)Antibiotics 2)Immunoglobulin G replacement
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What are the blood results of someone with SCID?
Normal levels of IgG, no IgA and reduced IgM Lymphocyte markers show absent/reduced T and NK cells but present B cells
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What are the treatments for SCID?
Paediatric emergency Antibiotics, antivirals, antifungals Asepsis Haemopoietic stem cell transplant (only cure) ?screen
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What is SCID?
Severe Combined Immunodeficiency - defect in T-cells no mature T cells on circulation
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What are the 3 causes of SCID?
1_Defect/absence of critical T cell molecule- TCR, common gamma chain 2)Loss of communication -MHCII deficiency 3)Metabolic -Adenosine deaminase deficiency
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Other cards in this set

Card 2

Front

Describe innate immunity

Back

General, not antigen specific but can recognise broad classes e.g. bacteria Rapid speed of onset Does not alter on repeated exposure No memory

Card 3

Front

Describe adaptive immunity

Back

Preview of the front of card 3

Card 4

Front

Define immunodeficiency

Back

Preview of the front of card 4

Card 5

Front

What is primary and secondary immunodeficiency?

Back

Preview of the front of card 5
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