Immunology Flashcards

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1
Q

HIV

A

Retrovirus infects CD4 cells - macrophages, dendritic cells, CD4 T lymphocytes

Most infections HIV 1 (W. Africa endemic HIV2)
Transmission via body fluids - blood, semen, vaginal secretions, breast milk

Risk factors:
MSM
IV drugs
Blood products before mid 1980s
Needle sticks
Multiple sexual partners
Sexual partners of high risk individuals
Infants born to infected mothers
Unprotected anoreceptive sex
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2
Q

Acute retroviral syndrome

A

Occurs 2-4 weeks after initial infection, lasts about 2 weeks

Presentation:
Persistent fever
myalgias
fatigue
headache
sore throat
rash
LAD
mucosal ulcers
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3
Q

Screening tests for HIV

A

Combined immunoassay:

  • HIV 1 and HIV 2 Ab
  • HIV 1 p24 Ag

If reactive -> Ab differentiation assay
-If nonreactive or indeterminate -> HIV1 nucleic acid testing

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4
Q

CD4 count

A

Normal 600-1500

used to track disease progression
used to measure clinical improvement during treatment

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5
Q

HIV Viral load

A

PCR measurement of virus particles in a blood sample

Used to measure effectiveness of antiretroviral therapy

May be used to detect acute HIV infection

Use to screen babies (Ab and Ag tests not accurate)

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6
Q

Treatment given to neonates born to HIV infected mothers

A

Zidovudine x 6 weeks
Retest and continue if infected
No breast feeding in US

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7
Q

Basic components of HAART

A

2 NRTIs + 1 NNRTI or Protease inhibitor boosted with ritonavir or integrase inhibitor

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8
Q

Occupational HIV exposure

A

HIV Ab testing immediately, at 6 weeks, at 3 mo, at 6 mo

PEP x 4 weeks

  • Tenofovir
  • Emtricitabine
  • Raltegravir
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9
Q

Thymic aplasia (DiGeorge Sn)

A

22q11 deletion

3rd and 4th pouches fail to develop

  • No thymus -> no mature T cells
  • No parathyroids -> hypocalcemia -> tetany

Recurrent viral, fungal, protozoal infections

Congenital defects in heart/great vessels

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10
Q

Chronic mucocutatneous candidiasis

A

T cell dysfunction v. C. albicans

Tx: antifungals - ketoconazole, fluconazole

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11
Q

Bruton agammaglobulinemia

A
X linked (Boys)
B cell deficiency -> defective tyrosine kinase gene -> low levels of all Ig
recurrent Bacterial infections after 6 mo - unencapsulated, extracellular
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12
Q

Selective immunoglobulin deficiencies

A

IgA (MC)
-most appear healthy
-Sinus and lung infections, GI infections
European descent
Assoc with atopy, asthma, celiac dz
Possible anaphylaxis to blood transfusions and blood products

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13
Q

Severe combined immunodeficiency (SCID)

A

total loss of adaptive immunity - T and B cells

Defective in early stem cell differentiation
Adenosine deaminase deficiency - AR -> elevated purines -> cell reproduction shuts down

Triad:
Severe recurrent infections
-Chronic mucocutaneous candidiasis
-Fatal or recurrent RSV, VZV, HSV, measles, flu, parainfluenza
-PCP pneumonia
Chronic diarrhea
FTT

CXR: no thymic shadow
No live vaccines

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14
Q

Ataxia telangiectasia

A

ATM gene - repair DNA breaks

IgA deficiency and T cell deficiency -> sinus and lung infections

Cerebellar Ataxia and poor smooth pursuit of moving target with eyes

Telangiectasis of face (after 5 yo)
Avoid XRs - sensitivity to radiation

Increased risk: lymphoma and acute leukemias

+/- elevated AFP after 8 mo - screening

Average age of death - 25 yo

"ATAXIA"
Ataxia
Telangiectasia
Acute leukemia/lymphoma risk
Xray sensitivity
IgA deficiency
AFP
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15
Q

Wiskott-Aldrich syndrome

A

WASP gene - active cytoskeleton movements in hematopoietic cells -> abnormal immune cells and platelets

"WAITER"
Wiskot
Aldrich
Immunodeficiency
Thrombocytopenia and purpura
Eczema
Recurrent pyogenic infections

X linked

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16
Q

Chronic granulomatous disease

A

X linked
Lack of NADPH oxidase -> phagocytes cannot destroy catalase positive microbes

Susceptible to S. aureus, Aspergillus, Listeria, Shigella, Salmonella, Pseudomonas, TB
-> PNA, abscesses, sepsis

Dx: negative nitroblue tetrazolium (NBT) test
-no yellow to blue-black oxidation

Tx:
ppx TMP-SMX and itraconazole
IFN-gamma helpful

17
Q

Chediak-Higashi syndrome

A

defective LYST gene (lysosomal transport)
Defective phagocyte lysosomes -> giant cytoplasmic granules in PMNs are diagnostic

Triad:
Partial albinism - poor melanosome transport
Recurrent respiratory tract and skin infections
Neurologic disorders (peripheral neuropathy, ataxia, seizures)

18
Q

Hyper-IgE syndrome (Job syndrome)

A

AD
Mutation for STAT3
->impaired differentiation of Th17 cells
->impaired recruitment of neutrophils

High levels of IgE and Eosinophils

Triad:
Eczema
Recurrent cold S. aureus abscesses
Coarse facial features: broad nose, prominent forehead “frontal bossing”, deep-set eyes, “doughy” skin

Common to have retained primary teeth resulting in two rows of teeth

19
Q

Leukocyte adhesion deficiency syndrome

A

Abnormal integrins -> inability of phagocytes to exit cirucation

Delayed separation of umbilical cord (weeks)
High risk of bacterial infections

20
Q

Anaphylaxis

A
Causes:
Drugs - PCN, sulfa drugs
Insect stings - bee, wasp
Latex
Foods - eggs, nuts, seafood

Features:
reaction within minutes, less than an hour of allergen exposure
Pruritis, urtircaria, bronchospasm, wheezing, angioedema (anywhere lips to larynx), diarrhea
Hypotension, shock, reflex tachycardia, syncope

Tx:
ABCs
Stop offending agent
Epi - may need repeated doses
Antihistamines for cutaneous sxs - H1and H2 blockers
Bronchodilators - albuterol, levalbuterol
Glucocorticoids

21
Q

Differential diagnosis for serum eosinophilia

A

“CANADA-P”

Collagen vascular disease - PAN, dermatomyositis
Atopic disease - allergies, asthma, Churg-Strauss, allergic bronchopulmonary aspergillosis
Neoplasm
Adrenal insufficency (Addison dz)
Drugs - NSAIDs, PCNs, cephalosporins
Acute interstitial nephritis - drug induced nephritis, allergic interstitial nephritis - abx, NSAIDs
Parasites - Strongyloides, Ascaris -> Loffler eosinophilic pneumonitis

Other: HIV, hyperIgE sn, coccidioidomycosis

22
Q

Neutropenia

A
Causes:
Viral - HIV, EBV, viral hepatitis
Aplastic anemia - radiation, Parvo B19
Chemo
Drugs - clozapine

Features:
Increased susceptibility to infections esp bacterial
neutrophil count less than 500

Tx:
G-CSF - filgrastim
GM-CSF - sargramostim
Glucocorticoids

23
Q

Management of febrile neutropenia

A

admit
Send pan cxs - blood, sputum, +/- CSF
Start empiric abs IV pip-tazo, meropenem, or cefepime

24
Q

Graft vs Host disease

A

Donor BM (graft) attacks recipient (host)

Sxs:
maculopapular rash
Abd pain
N/V/D
Recurrent infections
Easy bleeding

Dx:
elevated LFTs
low Ig
low platelets

Bx: skin and liver - inflammatory reaction with significant cell death

Tx:
corticosteroids
Tacrolimus
Mycophenolate