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π“˜π“‚π“‚π“Šπ“ƒπ‘œπ“π‘œπ‘”π“Ž > Immunodeficiency > Flashcards

Immunodeficiency Flashcards

1
Q

What is a primary (congenital) immunodeficiency?

A

➝ a defect in the immune system

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2
Q

What is a secondary (acquired) immunodeficiency?

A

➝ caused by another disease

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3
Q

What are three clinical features of immunodeficiency?

A

➝ Recurrent infections
➝ severe infections with unusual pathogens (aspergillus)
➝ unusual sites (liver abscess)

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4
Q

What are 6 signs of primary immunodeficiency?

A

➝ failure of an infant to gain weight or grow normally
➝ recurrent, deep skin or organ abscesses
➝ need for IV antibiotics to clear infections
➝ 2 or more deep seated infections
➝ family history of primary immunodeficiency
➝ persistent thrush after age 1

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5
Q

Where do you usually get infections in primary immunodeficiency?

A

➝ upper respiratory tract

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6
Q

What are 5 major B lymphocyte disorders?

A 
➝ X linked agammaglobulinaemia
➝ common variable immunodeficiency CVID
➝ selective IgA deficiency 
➝ IgG2 subclass deficiency 
➝ Specific Ig deficiency with normal Igs
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7
Q

What is the frequency for the components of the immune system affected in primary immunodeficiency?

A

➝ antibody : 50%
➝ T cell : 30%
➝ Phagocytes : 18 %
➝ complement : 2%

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8
Q

Where is the defect in X linked agammaglobulinaemia?

A

➝ BTK gene (X chromosome)

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9
Q

What does the BTK gene encode?

A

➝ Bruton’s tyrosine kinase

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10
Q

Describe what would normally happen when a pre B cell expresses BTK?

A

➝ The BTK is downstream to the pre-B cell receptors
➝ if there is recognition of self-antigen the receptor has to send a signal via the Brutons tyrosine kinase
➝ the signal will rescue the cell from the default fate of apoptosis and it progresses to the next stage

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11
Q

What happens in patients with defective BTK?

A

➝ the cell dies by apoptosis because it cannot progress onto the next stage

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12
Q

What kind of infections do people with X linked agammaglobulinaemia get and where?

A

➝ recurrent bacterial infections

➝ lung, ears, GI

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13
Q

What are the results of investigations for someone who has X linked agammaglobulinaemia (immune cell levels)?

A

➝ B cells absent/low
➝ Plasma cells absent
➝ all Igs absent/very low
➝ T cells and T cell mediated responses are normal

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14
Q

What is the treatment for agammaglobulinaemia?

A

➝ IV Ig 200-600mg/kg/month at 2-3 week intervals

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15
Q

What should you not give to people who have X linked agammaglobulinaemia?

A

➝ Live vaccines

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16
Q

What are 3 examples of predominant T cell disorders?

A

➝ DiGeorge syndrome
➝ Wiskott-Aldrich syndrome
➝ Ataxia-telangiectasia

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17
Q

What cells does SCID involve?

A

➝ both T cells and B cells

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18
Q

What is the mode of inheritance of SCID?

A

➝ 50-60% X linked

➝ rest are autosomal recessive

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19
Q

What is the presentation of SCID?

A

➝ Well at birth but problems occur after the first month
➝ diarrhoea, weight loss, persistent candidiasis
➝ severe bacterial/viral infections
➝ failure to clear vaccines
➝ unusual infections (CMV, pneumocystis)

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20
Q

What can be the 3 causes of SCID?

A

➝ Common cytokine receptor γ chain defect
➝ RAG-1/RAG-2 defect
➝ Adenosine deaminase deficiency

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21
Q

What does having a gamma chain defect affect?

A

➝ signal transducing component of of receptors for IL-2, IL-4, IL-7, IL-9, IL-11, IL-15, IL-21

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22
Q

What is IL-7 needed for?

A

➝ survival of T cell precursors

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23
Q

What happens if IL-7 is absent?

A

➝ Defective T cell development

➝ Lack in B cell help

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24
Q

What happens with an adenosine deaminase deficiency?

A

➝ accumulation of deoxyadenosine and deoxy ATP

➝ toxic for rapidly dividing thymocytes

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25
What are the results of investigations in people who have SCID (immune cell levels)?
``` ➝ very low/absent T ➝ normal/absent B ➝ sometimes also absent NK (γ chain defect affecting IL-15 receptor) ➝Igs low ➝ reduced proliferation and cytokines ```
26
What are the 6 treatments for people with SCID?
➝ isolation ➝ blood products from CMV negative donors ➝ IV Ig replacement ➝ treating infections ➝ bone marrow/haematopoietic stem cell transplant ➝ gene therapy for ADA and γ-chain genes
27
What is the survival for someone with SCID with an early diagnosis, a good donor match and no infections pre-transplant?
➝ >80%
28
What is the survival for someone with SCID with a late diagnosis,chronic infection and poorly matched donors?
➝ <40%
29
What is DiGeorge syndrome also called?
➝thymic hypoplasia
30
What is the cause of DiGeorge syndrome?
➝ Failure of development of the 3rd and 4th pharyngeal pouches ➝ one of the pouches is the thymus
31
What is the phenotype for DiGeorge syndrome?
➝ Cleft palate ➝ low set ears ➝ fish shaped mouth
32
What are the physiological abnormalities in DiGeorge syndrome?
➝ Hypocalcaemia ➝ Cardiac abnormalities ➝ Variable immunodeficiency (absent/reduced thymus which affects T cell development)
33
What is the mode of inheritance for Wiskott-Aldrich syndrome?
➝ X linked
34
What is the cause of Wiskott-Aldrich syndrome?
➝ defect in WASP ( protein involved in actin polymerisation) | ➝ when T and B cells signal they need to remodel their cytoskeleton
35
What happens in Wiskott-Aldrich syndrome?
➝ progressive immunodeficiency ( T cell loss) ➝progressive decreased in T cells and T cell proliferation ➝ Ab production
36
What are the antibody levels like in Wiskott-Aldrich syndrome?
➝ decreased IgM, IgG | ➝ increased IgE, IgA
37
What is the mode of inheritance of ataxia telangiectasia?
➝ Autosomal recessive
38
What is the cause of ataxia telangiectasia?
➝ Defect in cell cycle checkpoint gene (ATM)
39
What is the function of the ATM protein?
➝ sensor of DNA damage ➝ activates p53 ➝ causes apoptosis of cells with damaged DNA
40
How does an ATM mutation affect the immune system?
➝ ATM stabilises DNA double strand break complexes during VDJ recombination ➝ If ATM is mutated then there is a defect in generation of lymphocyte antigen receptors and lymphocyte development
41
What are the symptoms of ataxia telangiectasia?
➝ Progressive cerebellar ataxia ➝ typical telangiectasis ➝ immunodeficiency ➝ increased incidence of tumors later in life
42
What are the two types of defects in innate immunity?
➝ complement defects | ➝ phagocyte defects
43
What are 3 examples of phagocyte defects?
➝ Chronic granulomatous disease ➝ Chediak-Higashi syndrome ➝ Leukocyte adhesion defects (LADs)
44
What is the cause of chronic granulomatous disease?
➝ mutation in phagocyte oxidase (NADPH) components
45
How do reactive oxygen species form normally?
➝ In a phagocyte after the microbe is taken up there is the formation of active NADPH complexes by recruiting some subunits from the cytosol ➝ these convert oxygen into superoxide anions that are used to generate reactive oxygen species
46
How do granulomas form in granulomatous disease?
➝ There are defects in the components that lead to the formation of the superoxide anions ➝certain pathogens will not be able to be eliminated ➝ the formation of granulomas occurs (wall off the microbes) to try and contain the spreading of the infection to the rest of the body
47
What are the two tests for chronic granulomatous disease?
➝ NBT test | ➝ Flow cytometry assay dihydrorhodamine
48
How does the NBT test work?
➝ Neutrophils are taken from patients and controls ➝ incubated with nitroblue tetrazolium ➝ activate them with a microbe or with cytokines to check if they can produce reactive oxygen species ➝ if they can produce them they will generate a blue color in the NBT
49
How does the flow cytometry assay for chronic granulomatous disease?
➝ activate the neutrophils | ➝ if they can produce ROS they will cleave the dihydrorhodamine
50
What is the cause of Chediak Higashi syndrome?
➝ Defect in the LYST gene (regulates lysosomal traffic) | ➝ neutrophils have defective phagocytosis
51
Why does having Chediak Higashi lead to recurrent infections?
➝ defect in phagosome-lysosome fusion ➝ defective killing of phagocytosed microbes ➝ recurrent infections
52
What three things about neutrophils point to a Chediak Higashi diagnosis?
➝ decreased numbers of neutrophils ➝ neutrophils have giant granules because the lysosomes can't fuse properly ➝ they fuse with each other and not the phagosomes
53
What is the cause of LAD (leukocyte adhesion deficiency)?
➝ defect in β2 chain integrins (LFA-1, Mac-1) | ➝Defect in sialyl-Lewis X (selectin ligand)
54
How do you diagnose LAD?
➝ Delayed umbilical cord separation ➝ diagnosis defect in β2 chain integrins (LFA-1, Mac-1)
55
What is the presentation of LAD?
➝ SKin infections | ➝ intestinal and perianal ulcers
56
What are the lab investigation results for LAD (immune cell count)?
➝ Decreased neutrophil chemotaxis | ➝ Decreased integrins on phagocytes (flow cytometry)
57
What are the 4 types of complement deficiency outcomes?
➝ Recurrent infections ➝ Severe/fatal pyogenic bacteria ➝ SLE like syndrome ➝ Hereditary angioneurotic oedema
58
What do complement deficiency symptoms depend on?
➝ C factor affected
59
What complement factor is deficient if you have recurrent neisseria infections?
➝ Deficiency terminal complex (MAC) : C5,C6,C7,C8, C8 & C9
60
What complement factor is deficient if you have recurrent pyogenic bacteria infections?
➝ C3 deficiency
61
What complement factor is deficient if you have SLE-like syndrome?
➝C1q, C2,C4
62
What is hereditary angioneurotic oedema?
➝ failure to inactivate the complement | ➝ deficiency in C1 inhibitor
63
What does hereditary angioneurotic oedema lead to?
➝ Intermittent acute oedema skin/mucosa leading to vomiting, diarrhoea, airway obstruction
64
What are the two investigations for complement deficiencies?
➝ Complement function : CH50 | ➝ measure individual components
65
What are the 6 treatments for primary immunodeficiency?
``` ➝Immunoglobulin replacement therapy ➝Bone marrow transplantation ➝Gene therapy ➝Prompt treatment of infection ➝Prevention of infection : isolation, ➝prophylaxis, vaccination ➝Good nutrition ```
66
What are the 8 causes for secondary immunodeficiency?
``` ➝Infections : viral,bacterial ➝Malignancy ➝Extremes of age ➝Nutrition (anorexia, iron deficiency) ➝Chronic renal disease ➝Splenectomy ➝trauma/surgery, burns, smoking, alcohol ➝Immunosuppressive drugs ```
67
What are the 4 infections that cause secondary immunodeficiencies?
➝Viral : HIV,CMV,EBV,measles, influenza ➝Chronic bacterial : TB, leprosy ➝Chronic parasitic : malaria, leishmaniasis ➝Acute bacterial : septicaemia
68
What are the 3 malignancies that cause secondary immunodeficiencies?
➝Myeloma ➝Lymphoma (Hodgkin’s, non-Hodgkin’s) ➝Leukaemia (acute or chronic)
69
What would cause an infant to be Ig deficient?
➝ Premature delivery
70
What two age groups have secondary immunodeficiency?
➝ Premature | ➝ old age

π“˜π“‚π“‚π“Šπ“ƒπ‘œπ“π‘œπ‘”π“Ž (14 decks)

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