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Emma > Immunodeficiencies > Flashcards

Immunodeficiencies Flashcards

1
Q

A crucial part of innate immunity is the involvement of neutrophils. What are their functions?

A

Chemotaxis (C3a/C5a –> chemokines)
Phagocytosis (Opsonization: IgG + C3b enhance this)
Killing (Lysosomal granules contain many bactericidal agents)

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2
Q

Defects of Neutrophil function (Inability to mount a normal inflammatory response)

A
  1. Neutropenia- low neutrophil count e.g. patients receiving chemotherapy
  2. Defective opsonization (IgG deficiency, C3b deficiency *rare)
  3. Non-killing neutrophils
    - Chronic granulomatous disease (CGD)
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3
Q

Chronic granulomatous disease (CGD)

A

Non-killing neutrophils

  • X-linked (*males)
  • defect in cytochrome b and NADPH oxidase –> no superoxide anion prod, cant kill staph
  • recurrent infection with abscess of skin, lymph nodes, CHRONIC GRANULOMAS
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4
Q

Neutropenia

A
  • Defective opsonization (mediated by IgG + C3b).
  • Defective inflammatory response (chemotaxis by C3a + C5a).
  • Defective phagocytosis.
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5
Q

Under normal circumstances, ______________ in the neutrophil cytoplasm collide with the phagosome and release their granules containing numerous bactericidal enzymes and ____________.

A

lysosomal granules

superoxide anion.

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6
Q

Leukocyte Adhesion Deficiency (LFA-1 deficiency)

A
  • Neutrophils fail to emigrate out of vessels towards the ag (no sticking to endothelial cells)
  • Failure of CD8+ cells to bind to target cells
  • Recurrent bacterial infection
  • Failure to heal wounds (Umbilicus)
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7
Q

Chediak Higashi Syndrome

A
  • Giant Lysosomal Granules
  • Defective phagosome-lysosomal fusion in neutrophils
  • Recurrent infection
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8
Q

Neutrophil defect immune deficiencies

A
  1. Neutropenia
  2. CGD
  3. Leukocyte Adhesion Deficiency (LFA-1)
  4. Chediak-Higashi Syndrome
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9
Q

X-Linked Agammaglobulinemia

A
  • “Brunton’s agammaglobulinemia”
  • Absent IgG, IgA and IgM
  • Pre-B cells in marrow, but no mature B-cells
  • Absent or very small tonsils and lymph nodes
  • Btk mutation (TYR KINASE imp for light chain rearrang.)
  • Absent germinal centers in lymph nodes, absent B-cells in blood
  • recurrent infections

*boys

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10
Q

Serum electrophoresis from 1) a normal person and 2) a patient with X-linked agammaglobulinemia

A

(absent gamma-globulin band)

Normal VDJ recombination of µ light chains in pre-B-cells, but no class switching.

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11
Q

Management of X-Linked Agammaglobulinemia

A

Avoid infections where possible
Abx
Intravenous immunoglobulin (IVIG) every 3 weeks
3 weeks for IVIG to drop, then give another shot

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12
Q

IgA Deficiency

A
  • Common 1:700
  • many pt asymptomatic
  • Pt w/ associated IgG2 or IgG4 deficiency –> severe respiratory and GI infections
  • IVIG is not usually helpful
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13
Q

Hyper IgM syndrome

A
  • mut CD40L gene (on TCell)
  • Failure of isotype switching
  • Only IgM and IgD. NO switch to IgG, IgA or IgE
  • NO germinal centers. Most cells are T cells.
  • Recurrent infections
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14
Q

Transient Hypogammaglobulinemia of Childhood

A
  • Delay in the production of normal Abs
  • B-cells are present
  • Transient ability to prod IgG
  • Cause is unknown, may be due to deficiency in #/function of helper T cells
  • Resolves with time
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15
Q

Common Variable Immunodeficiency

A
  • not common. Appears in teens/adults
  • Low serum levels of all immunoglobulins
  • B-cells are present, but defective differentiation into plasma cells
  • Increased susceptibility to infections
  • Defect unknown (poss defect B-cells –> plasma cells)
  • tx:IVIG

Humoral deficiency

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16
Q

Di George Syndrome

A

(chromosome 22q11.2 deletion syndrome (22qDS)

-No T-cells, no B-cell class switching

1) Cardiac anomalies
2) Hypoplastic thymus or complete ABSENCE of the thymus.
3) Hypocalcemia (resulting from parathyroid hypoplasia).
4) Facial abnormalities e.g. cleft palate
Majority of patients with DGS have deletions in chromosome 22q11.2.

  • recurrent infections with intracellular bacteria,
    fungi, large viruses (also pyogenic organisms bc lack of T-cell help for B-cells)
17
Q

Di George Syndrome CATCH 22

A 
Cardiac abnormality 
Abnormal facies
Thymic aplasia
Cleft palate
Hypocalcemia.
18
Q

Patients with Di George syndrome will have:
A) Decreased numbers of surface IgM and IgD positive B-cells
B) Normal serum IgE levels
C) Normal serum anti-influenza IgG levels after immunization with the influenza vaccine
D) Normal ability to produce acute phase proteins such as CRP
E) Normal IL-2 production

A

D

19
Q

Severe Combined Immunodeficiency

A
  • Numerous forms of SCID that can result from any one of several genetic defects.
  • Both humoral and cell mediated immunity are defective.
  • Patients are susceptible to all infectious agents (severe oral esophageal/nail candidiasis)

Tx: reconstitution of immune system with stem cell transplantation *beware of GVH

20
Q

The commonest form of SCID

A
  • mutation of the common-chain of the IL-2 Receptor

- X-linked severe combined immunodeficiency

21
Q

Adenosine deaminase (ADA) deficiency

A

Form of SCID

22
Q

Bare lymphocyte syndrome

A 
Form of SCID
Cells lack class I or II MHC molecules
23
Q

Abnormal signal transduction leading to SCID

A

1) Mutations of protein kinases e.g. JAK3 or ZAP 70

2) Mutations of RAG1 and RAG2

24
Q

Mutations of the CD3 molecule
Defective Cytokine production

Can lead to …

A

SCID

25
Q

Wiskott Aldridge Syndrome

A

Immunodeficiency
Defective WAS (necessary for for cytokine release).
Thrombocytopenia (low platelet count) - purpuric spots
Eczema (Elevated IgE, type I allergic rxn)
Recurrent infections

tx: stem cell transplant

26
Q

Ataxia Telangiectasia

A

Defective DNA repair, causing a type of SCID.

Sx: Ataxia
Telangiectasia (of eye) (spider-like vascular abnormalities)

no curative tx

27
Q 
Secondary Immunodeficiency
(Defective humoral immunity)
A

Lymphoma
Myeloma
Burns

(loss of Ig in serum)

28
Q 
Secondary Immunodeficiency
(Defective Cell mediated Immunity)
A

Patients taking Immunosuppressive drugs
Malnutrition
Viral infections especially HIV
Ageing

29
Q

Acquired Immunodeficiency Syndrome (HIV)

A

HIV virus infects the CD4 cell

Viral gp120 binds to the CD4 molecule
Gp41 binds to the chemokine receptor CCR5

T cells drop dramatically

30
Q

Clinical course of HIV disease

A

4-6 weeks T cells drop to about half of what they should be.
Then stabilize at about half their normal level (clinical latency)

Virus goes sky high, drops, continues for months/years (clinical latency), then suddenly goes up. Infections, death.

31
Q

Laboratory diagnosis of HIV

A

1) Can detect HIV antigen or antibody in the blood
2) Reversal of the CD4:CD8 ratio. This ratio is normally approximately 2:1
3) Measure serum levels of HIV RNA to follow progress of the disease.

32
Q

The commonest immunodeficiency ….

A

Ageing is associated with significant and continuous immune deficiency

Decreasing number and function of many cell types including, neutrophils, antigen presenting cells, NK cells, and T-cells

33
Q

Specific immunodeficiency to papilloma virus

A

causing very severe warts

Pt responded normally to PPD and to other delayed hypersensitivity skin tests (normal cell mediated immunity)

cause unknown

34
Q

Chronic mucocutaneous Candidiasis

A

Lack of IL-17 production or Autoantibody to IL-17

35
Q

B-cell defect immune deficiencies

A
  1. Brunton’s (X-linked) aggamaglobulinemia
  2. IgA deficiency
  3. Hyper-IgM syndrome
  4. Transient Hypogammaglobulinemia of Infancy
  5. Common Variable Immunodeficiency
36
Q

T-cell/SCID defect

A
  1. DiGeorge Syndrome
  2. T-cell Activation Defects
  3. Severe Combined Immunodeficiency
  4. Bare Lymphocyte Syndrome
  5. Wiskott-Aldritch Syndrome
  6. Ataxia Telangiectasia
37
Q

SCID (other forms)

A
  1. adenosine deaminase (ADA) deficiency
  2. bare lymphocyte syndrome
  3. abnormal signal transduction
    - mut JAK3 or ZAP70 (protein kinases)
    - mut RAG1 and RAG2
  4. CD3 mutation
  5. defective cytokine prod
38
Q

Susceptibility to opportunistic infections

A

T-cell deficiencies like DiGeorge, SCID, Bare lymphocyte syndrome, HIV, mutation of CD3

*NOT B-cell deficiency (like X-linked aggamaglobulinemia)

Emma (18 decks)

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