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Immunodeficiency Flashcards

1
Q

Immune disorder associated with this pathogen: mycobaterium

A

cellular immunity

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2
Q

Immune disorder associated with this pathogen: gram + and gram - bacteria

A

neutrophil defect

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3
Q

Immune disorder associated with this pathogen: enterovirus

A

antibody defect

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4
Q

Immune disorder associated with this pathogen: staphylococcus

A

complement deficiency

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5
Q

Immune disorder associated with this pathogen: neisseria

A

complement deificency

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6
Q

Immune disorder associated with this pathogen: haemophilus influenza

A

antibody defects

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7
Q

Immune disorder associated with this pathogen: salmonella

A

type 1 cytokine defects and cell mediated defects

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8
Q

Immune disorder associated with this pathogen: mycoplasma

A

antibody defects

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9
Q

Immune disorder associated with this pathogen: herpes virus

A

defects with cell-mediated immunity

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10
Q

What are possible clinical clues to an underlying immunodeficiency? (x5)

A
  • increased frequency of infections
  • infection of unusual severity (aggressive Abs, surgical drainage)
  • complicated infections (spread to other organ systems)
  • infections of excessive duration
  • infection by an unusual organism (eg fungi, intracellular)
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11
Q

B Cell (antibody) deficiency results in susceptibility to which infections (body system and pathogen)?

A

1) Recurrent sinopulmonary and gut infections:

  • sinusitis, bronchitis, tonsilitis, otitis media
  • bacterial pneumonia
  • bronchiectasis (long-term)
  • skin infections
  • infectious diarrhoea

2) Infections by:

  • polysaccharide encapsulated pyogenic organisms
    • strep pneumoniae
    • H influenzae type b
    • strep pyogenes
    • branhamella catarrhalis
  • staph aureus
  • giardia lamblia
  • campylobacter jejuni
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12
Q

T cell deficiency results in infection by which pathogens/

A

Intracellular (as per AIDS)

  • Fungi (eg mucosal candidiasis)
  • Viruses: CMV, VZV, HSV, protozoa eg pneumocystis
  • Listeria
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13
Q

Neutrophil/monocyte deficiency results in infection by which pathogens?

A

High grade bacterial infections

  • Staph aureus
  • Gram negative bacteria:
    • E coli
    • Proteus mirabilis
    • Serratia marcescens
    • Pseudomonas aeruginosa and cepacia

Fungi

  • Invasive Aspergillus
  • Systemic candidiasis
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14
Q

Complement pathway deficiencies result in which disease processes (for classical, alternate and terminal)?

A

Classical

  • C1q, C1r, C1s : SLE
  • C4 : SLE, GN
  • C2 : SLE (50%), vascullitis, GN
  • C3 : recurent pyogenic infections, GM, immune complex diseases

Alternate

  • Properdin : Neisseria infections
  • Factor D : other pyogenic infections

Terminal components

  • C5, 6, 7, 8, 9 : disseminated Neisseria infections (gonococcal and meningococcal)
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15
Q

What investigations should be ordered (most appropriately) for a suspected Antibody Deficiency?

A

Ig levels (G, A, M, E)

EPG (total gamma reflects Ig)

B cell counts

Vaccine responsiveness

  • antibodies to tetanus and diptheria (assume previous vaccination)
  • dynamic antibody response to vaccination (polysaccharide antigen eg Pneumovax/Hib, or protein conjugate vaccine eg Prevenar)
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16
Q

What investigations should be ordered (most appropriately) for a suspected T cell deficiency?

A

T cell subsets

  • About 2/3 of lymphocytes are T cells (CD3), about 2/3 of T cells are T Helper cells (CD4), lost in HIV infection
  • CD8= cytotoxic T cells, usually increased in reactive viral conditions eg HIV/EBV
  • CD4:CD8 usually approx 2:1

HIV serology

consider CXR ?thymus

17
Q

What investigations should be ordered (most appropriately) for a suspected complement deficiency?

A

CH50: complement screen, if abnormal can assess each component of the cascade independantly

C3, C4 easiest to measure

AH50 assesses the common (terminal pathway), if abnormal, suggests C5-9 deficiency

*NB most common cause of abnormal CH50 is delayed transport to the lab–> repeat!!

18
Q

What investigations should be ordered (most appropriately) for a suspected neutrophil disorder?

A

Neutrophil differential count

Neutrophil oxidative metabolism tests (activated neutrophils generate reactive oxygen species for microbicidal action)

  • Nitroblue tetrazolium (NBT) test (respiratory burst test); dye reduction
  • Flow cytometry: dihydrorhodamine reduction
  • Chemiluminescence

Chemitaxis and adhesion tests

  • Slide test
  • Boyden chamber
19
Q

What are the features of Common Variable Immunodeficiency (CVID)?

  • Incidence, M/F, age
  • Clinical features
  • Investigations
  • Complications
  • Treatment
  • Prognosis
  • Genetics
A

Incidence, M/F, age

  • most common PID in adults req Rx, 1:10,000-1:100,000
  • M=F
  • 2 peaks at 1-5yrs of age and 18-25 yrs of ageClinical features
  • recurrent sinopulmonary infections: pneumonia, sinusitis, bronchitis, tonsillitis, otitis media
  • GIT: chronic or recurrent diarrhoea, malabsorption and LoW/FTT
  • Skin infections
  • T cell infections uncommon but increased
  • Autoimmunity: immune cytopenias ITP/AIHA, thyroid, pernicious anaemia, polyarthropathy eg RA, polymyositis, vitiligo
  • Neoplasia: lymphoma (x400 for NHL), stomach Ca
  • Lymphoproliferation: lymphadenopathy, splenomegaly, granulomatous disease
  • Allergic disease: food allergy
  • Bronchiectasis and resp failure
  • Chronic infection eg amyloidosisInvestigations
  • IgG low, IgA/IgM one of or both low
  • B cell count approx N
  • EPG–> hypogamma
  • impaired vaccine response
  • exclude secondary cause: drugs, myeloma, lymphoma, nephrotic syndrome, GI protein lossComplications
  • bronchiectasis 27% (and resp failure)
  • chronic infection, amyloidosisTreatment
  • IVIG 0.4g/kg monthly, subcut inf weekly
  • antibiotics for infection: start early, treat longer, identify organism, prophylaxis
  • avoid live vaccines!!
  • monitor for Cx (pulm function tests, HRCT)

Prognosis

  • improved with IVIG (trough 5g/L reduced infection, 7g/L for well being)
  • higher mortality with: lower levels of IgG, abnormal T cell response, lower % B cells
  • increased cancer and autoimmunity

Genetics

  • Multiple, ICOS/CD19/CD81/CD20/CD21/BAFF-R/TWEAK defciency, TAC1 mutation
20
Q

What are the features of X-Linked Agammaglobulinaemia (Bruton’s)?

  • Age
  • Clinical features
  • Investigations
  • Complications
  • Treatment
  • Prognosis
  • Genetics/Aetiology
A

Age

  • Early onset (approx 6 mo) until then have maternal IgG

Clinical features

  • No lymphoid tissue
  • recurrent sinopulmonary/GIT infections: pneumonia, sinusitis, bronchitis, tonsillitis, otitis media
  • GIT: chronic or recurrent diarrhoea, malabsorption and LoW/FTT
  • polyarthropathy (RA)
  • chronic echovirus meningoencephalitis may be fatalInvestigations
  • Ig levels are typically undetectable
  • B cell count approx 0
  • No plasma cells or germinal centres in tissue biopsies
  • EPG–> hypogamma
  • B cell pre-cursors in bone marrow
  • Btk expression by flow cytometry and genetic analysis of Btk geneComplications
  • bronchiectasis 27% (and resp failure)
  • chronic infection, amyloidosisTreatment
  • IVIG 0.4g/kg monthly, subcut inf weekly
  • antibiotics for infection: start early, treat longer, identify organism, prophylaxis
  • avoid live vaccines!!
  • monitor for Cx (pulm function tests, HRCT)

Prognosis

  • early detection allows survival into adulthood

Genetics

  • FHx in 50%, rest are spont mutations
  • Absence /mutation of Bruton’s TYR kinase (signalling molecule essential for B cell development)
  • B cells are arrested at the Pre-B-I Stage in the bone marrow
21
Q

What are the features of IgA Deficiency?

  • Defect
  • Cause
  • Age of presentation
  • Clinical Features
  • Associations
  • Investigations
  • Treatment
A

Defect

  • Absence of IgA (+/- IgG subclasses)
  • Dysregulation in Ig isotype switching during B cell activationCause
  • usually sproadic, can be familial (some families with CVID)
  • Drug induced by phenyton, penicillamine
  • intrauterine infection
  • TORCHsAge of presentation
  • AnyClinical Features
  • most patients are asymptomatic: recruitment of oligomeric IgM into secretions
  • mucosal infections like CVID/XLA: sinopulmonary, giardiasisAssociations
  • Atopic disease, incl asthma
  • cow’s milk allergy
  • GIT disease: nodular lymphoid hyperplasia, coeliac, IBD
  • Autoimmune disorders: RA, JRA, SLE, DMS, Sjogren’s syndrome, ITP, pernicous anaemia, thyroiditis, Addison’s, AI-CAH
  • Anaphylaxis: after transfusion of IgA containing blood products due to anti-IgA antibodies
  • lymphoreticular malignancy (slight)Investigations
  • EPG–> normal
  • Ig levels –> absent IgA
  • B cell count–> normalTreatment
  • prompt Ab for acute episode
  • NOT IVIG: mucosal not systemic defect, maybe if assoc with IgG subclass deficiency
  • should transfuse with blood from IgA deficient donor or triple washed cells
22
Q

What are the features of IgG subclass deficiency?

  • Age
  • Clinical features
  • Investigations
  • Complications
  • Treatment
A

Four IgG subclasses, deficiency of a single class is controversial

Normal range for IgG4 includes 0

Any combination may be low, usually IgG2 or IgG3, if IgG1 low, usually total Ig low = often CVID

IgA def often associated

Age
  • Any (childhood normal ranges are difficult to define)Clinical features
  • recurrent sinopulmonary infectionsInvestigations
  • EPG–> normal
  • IgG levels–> normal or bordeline low
  • IgG subclasses–> deficiency in one or more
  • B cell count–> normalComplications
  • As for other Ab deficiency syndromesTreatment
  • Consider gammaglobulin replacement if high frequency of recurrent bacterial infections (does not fit IVIG guidelines in Australia)
23
Q

What are the features of a Specific Antibody Deficiency?

  • Age
  • Clinical presentation
  • Investigations
  • Treatment
A

Age

  • Any age (paediatric)Clinical presentation
  • recurrent URTIsInvestigations
  • Ig levels–> normal
  • B cells–> normal
  • Specific Ab to vaccination impaired (polysaccharide Pneumovax, conjugated to protein Prevenar) but little consensus about what constitutes a normal response or protective levelTreatment
  • Vaccination
  • IVIG
24
Q

What are the features of Hyper-IgM syndrome?

  • Aetiology
  • Age at onset
  • Clinical Features
  • Complications
  • Diagnosis
  • Treatment
A

Aetiology

  • X-linked CD40L deficiency
  • absent CD40-CD40L signal in T cell and B cell collaboration–> failure of B cell isotype switching and memory B cell formationAge at onset
  • 1-2 yrs of ageClinical Features
  • Recurrent bacterial infections: respiratory, especially PCP (some role for CD40L in T cell activation as well)
  • Acute/chronic diarrhoea: cryptosporidium, oral ulcers, proctitisComplications
  • increased incidence of malignancy and autoimmune disease
  • NeutropeniaDiagnosis
  • IgA, IgG, IgE –> low, IgM–> normal or high
  • B cells –> normal circulating, expressing IgM, IgD but not IgG, IgE, IgA
  • impaired antibody response to T cell dependant antigens
  • Flow cytometry for surface CD40L
  • molecular studiesTreatment
  • IVIG
  • Bactrim prophylaxis
  • G-CSF
  • ???BMT
25
Q

What are the features of Chronic Mucocutaneous Candidiasis?

  • Aetiology/Genetics
  • Clinical features
  • Investigations
A

Aetiology/Genetics

  • Lack of Th17 cells
  • Stat-1 gain of function mutation (assoc with autoimmune thyroid disease)
  • APECED (IL-17 and Il-22 antibodies)
  • Thymoma associatedClinical features
  • chronic/recurrent candidal infection
  • onset in childhood
  • affects skin, nails and mucosa (oesophageal and pulmonary)
  • other infections eg HSVInvestigations
  • Lack Th17 cells
26
Q

What are the features of Severe Combined Immunodeficiency (SCID)?

  • Aetiology
  • Clinical features
  • Treatment
A
  • Aetiology: lack of a component essential for T cell function
    • most common is defect on gene for gamma chanin (common to multiple cytokine receptors), X-linked
    • second most common is ADA deficiency (salvage pathyway of purine metabolism, required for DNA synthesis (lymphocytes are unable to divide appropriately), AR
    • AR other types
      • JAK3 deficiency- signalling cell from gamma chain
      • IL-7R aloha deficiency
      • ZAP70 deificency- tyrosine kinase essential for TCR signalling
      • CD3 deficiency
      • bare lymphocyte syndrome- MHC Class II deficiency
      • RAG1, RAG2 deficiency- genes for VDJ recombination
      • myeloid or reticular dysgenesis (defective maturation)
  • Clinical features
    • failure to thrive
    • chronic diarrhoea
    • recurrent opportunistic infections: fungal, viral, protozoal (eg PJP pneumonia), no B cell function secondary to lack of “help”
    • risk of malignancy and autoimmunity
    • absent lymphoid tissue (thymus)
    • ADA def associated with skeletal abnormalities
  • Treatment
    • BMT
    • enzyme replacement for ADA deficiency
27
Q

What are the features of Hyper IgE syndrome (Job’s syndrome)?

  • Clinical
  • Pathogenesis
  • Investigations
  • Treatment
  • Prognosis
A
  • Clinical: triad of recurrent staphylococcal infections (“cold” skin with minimal incr CRP, pneumonia), candida infections, elevated IgE (usually >2000)
  • Pathogenesis
    • AD-HIES patients have a Stat-3 mutation (signalling molecule in the cutokine response pathway (especially involved in Th17 development)–> Th17 deficiency
  • Investigations
    • raised IgE >2000 in most cases, tends to fall with age
    • other Igs normal
    • sometimes blunted specific antibody responses
    • eosinophilia in 60-93% (marked in AR, less in AD)
  • Treatment
    • Skin care- cleach bathes x3 per week
    • Ab prophylaxis (co-trim and antifungals)
    • surgical drainage of abscesses/excision of pneumatoceles
    • IVIG possible if poor Ab responses
  • Prognosis
    • AD survive to adulthood, AR lethal in childhood
28
Q

What are the features of chronic granulomatous disease (CGD)?

  • Molecular defect
  • Clinical features
  • Investigations
  • Treatment
A
  • Molecular defect
    • deficiency of i of the 4 subunits of NADPH oxidase (gp91 on the X chromosome)
    • respiratory burst of neutrophils is generally necessary to kill intracellular organisms
      • neutrophil recognises pathogen–> phagocytosis and fusion of pathogen and cellular granules–> cellular activation–> oxidative burst with generation of O2, H2O2 and NO
  • Clinical features
    • recurrent infection of: skin, lungs and other tissues, coag negative bacteria and fungi
    • staph infections of skin esp ears and nose, liver abscess (CGD until proven otherwise)
    • purulent dermatitis
    • lymphadenitis, often granulomatous
    • recurrent bronchopneumonia: hilar lymphadenoapthy, empyema, lung abscess
    • intestinal obstruction
    • Crohn’s like syndrome: perianal abscess/fistula, hepatosplenomegaly
    • osteomyelitis
    • aspergillus pneumonia, osteomyelitis, other tissues\
  • Investigations
    • tests ability of activated granulocytes to generate reactive oxygen species for microbicidal action
      • NBT test
      • chemiluminescence
      • flow cytometry for dihydrorhodamine reduction
  • Treatment
    • chronic Abs
    • Immunisation
    • interferon gamma
29
Q

DiGeorge syndrome:

  • Aetiology
  • Immunodeficiency
  • Clinical features
A
  • Aetiology
    • failure of development of the 3rd and 4th pharyngeal arches
  • Immunodeficiency
    • Variable degree of T cell immunodeficiency: most moderate, rarely severe
  • Clinical features
    • Cardiac abnormalitis
    • Abnormal facies
    • Thymic hypoplasia/aplasia
    • Cleft palate
    • Hypocalcaemia
    • 22q11-pter deletion
30
Q

Ataxia-telangietasia:

  • Aetiology
  • Clinical features
  • Investigation findings
  • Treatment
A
  • Aetiology
    • complex AR multisystem disorder
    • immunodeficiency and chromosomal instability
    • molecular defect
      • defect in the ATM (ataxia telangiectasia mutated gene), critical in cell cycle control and DNA damage response
      • chromosomal deletion or translocation–> Ig/TCR loci disrupted
  • Clinical features
    • cerebellar ataxia
    • oculomotor signs
    • telangiectasia
    • sinopulmonary infections: bronchiectasis
    • mental retardation
    • growth retardation
    • increased malignancy risk (lymphoid and other solid tumours)
    • radiation sensitivity
  • Investigation findings
    • low T cells, normal B cells
    • thymic hypoplasia
    • variable low Igs, especially IgA
  • Treatment
    • supportive
31
Q

Wiskott-Aldrich Syndrome

  • Inheritance
  • Aetiology
  • Clinical features
A
  • Inheritance: X-linked
  • Aetiology
    • defective WASP gene- involved in cytoskeletal reorganisation (during T cell activation)
  • Clinical features
    • thrombocytopenia with SMALL platelets (bleeding and bruising)
    • eczema, eosinophilia and food allergies
    • recurrent infections
      • respiratory tract
      • severe viral illnesses
32
Q

X-linked lymphoproliferative syndrome:

  • Clinical presentation
  • Aetiology
A
  • Clincal presentation
    • Fulminant EBV infection
      • uncontrolled expansion of EBV infection B cells and CD8 cells
      • haemophagocytic lymphohistiocytosis
    • Hypopgammaglobulinaemia +/- EBV infection
    • Lymphoma predisposition (mostly B cell in origin) +/- EBV infection
  • Aetiology
    • arises due to mutation in gene for SAP (SLAM associated protein)
    • adapter protein involved in intracellular signalling pathways
    • deficiency leads to increased survival of EBV infected/transformed B cells
33
Q

Leukocyte adhesion deficiency type 1

  • Aetiology
  • Clinical features
  • Investigation findings
  • Treatment
A
  • Aetiology
    • defect in beta subunit of beta-2 integrins (CD18)
  • Clincal features
    • onset at birth, delayed cord separation, omphalitis
    • failure to thrive
    • recurrent bacterial infection of the skin, mucous membranes, absence of pus formation
    • severe gingivitis and periodontitis
    • poor wound healing
  • Investigation findings
    • defective adhesion dependant neutrophil functions
    • defective expression of CD18
  • Treatment
    • BMT
    • Abs
    • granulocyte transfusions
34
Q

Leukocyte adhesion deficiency type 2:

  • Aetiology
  • Clinical features
  • Treatment
A
  • Aetiology
    • defect in fucose metabolism
    • deficienct expression of fucosylated carbohydrates including SLeX
    • failure of selectin function
    • leukocytes fail to roll
  • Clinical features
    • severe mental retardation
    • Bombay blood group (hh)
    • short stature and characteristic facial features
    • Similar immunodeficiency to LAD-1
      • onset at birth, delayed cord separation, omphalitis
      • failure to thrive
      • recurrent bacterial infection of the skin, mucous membranes, absence of pus formation
      • severe gingivitis and periodontitis
      • poor wound healing
  • Treatment
    • Abs
    • May become less severe with age

Immunology (13 decks)

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