BL - Immunodeficiency Flashcards

1
Q

DiGeorge syndrome

A

DiGeorge syndrome: abnormality in pharyngeal pouches forming thymus (and other associated structures)

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2
Q

Infections expected in pure B-cell vs pure T-cell deficiency

A

Pure B cell = high grade pathogens, extracellular, pyogenic bacteria: Staph aureus, Haemophilus influenza, Streptococcus pneumoniae
Pure T cell = intracellular pathogens: viruses, some bacteria, yeasts, fungi, Candida albicans, Pneumocystis jirovecii

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3
Q

Clinical features of DiGeorge syndrome

A

CATCH-22: cardiovascular issues, abnormal facial features, thymic aplasia, cleft palate, hypocalcemia/hypoparathyroidism, chromosome 22q deletion.

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4
Q

Selective IgA deficiency

A

Incidence about 1/500 people. Patients are often relatively asymptomatic other than diarrhea and sinopulmonary infections, or increased frequency and severity of allergies. 10-15x more frequent in individuals with celiac.

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5
Q

Enzyme-deficient SCID

A

Missing ADA – adenosine deaminase enzyme. Autosomal recessive inheritance. Can be transfused via irradiated RBCs – must be irradiated to kill all lymphocytes so as not to cause a reaction in an immunocompromised patient. Purified ADA can be administered as a drug when stabilized with PEG.

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6
Q

T- and B-cell areas in lymph node

A

B cells in lymphoid follicles (primary and secondary)

T cells in interfollicular area - paracortex

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7
Q

IVIG as treatment

A

IgG pooled from many donors, usually about 99% IgG. IVIG is administered monthly and has a half life of 3 weeks. Standard treatment is an IV administration (effective but expensive and short supply), slow subcutaneous infusion (SCIG) has been approved and can be done at home.
Useful in conditions where B-cell function is deficient: ex. Bruton’s agammaglobulinemia

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8
Q

Tests to determine type of immunodeficiency

A

B cells: serum protein electrophoresis, quantative Ab levels, specific Abs to prior immunizations, ABO isohemagglutinins
T cells: skin test with recall Ag panel, total lymphocyte count
Phagocytes: WBC count, differential, morphology; NBT test, oxidative burst
Complement: CH50, assay for C1 inhibitor

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9
Q

Transplantation therapy

A
Fetal thymus or cultured thymic stromal cells in DiGeorge to minimize GvH. 
Bone marrow transplant has about 50% success rate in SCID – donor must match recipient at at least one MHC class I locus and one MHC class II.
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10
Q

SCID

A

Abnormality of production in bone marrow. Neither pre-T nor pre-B cells are produced

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11
Q

X-linked (Bruton) hypogammaglobulinemia

A

Abnormality of production in bone marrow. Pre-B cells can’t be converted into B cells because of defect in btk gene

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12
Q

CVID

A

Abnormality of production in lymph node. B cells not triggered to make antibody properly

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13
Q

Hyper IgM syndrome

A

Defect in class switching from IgM -> IgG. T-cells stimulate B-cells to switch but process can’t be carried out properly

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