B AND T cell, Macrophage

Question 1

Ataxia Telangiectasia

Answer 1

Defect: Defects in ATM gene –> failure to repair DNA double strand breaks –> cell cycle arrest
Presentation:
- TRIAD: cerebellar defects (Ataxia), spider angiomas (telangiectasia), IgA deficiency
Findings:
Inc AFP
Dec IgA, IgG, and IgE
lymphopenia, and cerebellar atrophy

Question 2

Hyper IgM syndrome

Answer 2

B and T cell dysfunction
Defect: Most commonly due to defective CD40L on the Th cells –> class switching defect
- x-linked recessive
Presentation: Severe pyogenic infections early in life, oppurtunistic infection with Pneumocystitis, and cryptosproidium, cmv
Findings
Inc IgM,
big Dec IgA, G , E

Question 3

Wiskott- Aldrich syndrome

Answer 3

Defect: Mutation in WAS gene (x-linked recessive) –> T cells unable to re-organization actin cytoskeleton
Presentation
“WATER”
Wiskott-Aldrich, Thrombocytopenia, Eczema, Recurrent infections
Inc. risk of autoimmune disease and malignancy
Findings:
Dec to normal IgG, IgM
Inc IgE and IgA
Fewer and smaller platelets

Question 4

Leukocyte adhesion deficiency (Type 1)

Answer 4

Macrophage Defect
Defect in LFA-1 integrin (CD18) on phagocytes, impaired migration and chemotaxis,
- AR
Presentation
Recurrent bacterial skin and mucosal infections, absent pus formation, impaired wound healing, delayed separation of umbilical cord (>30DAYS)
Findings
- In neutrophils
- Absence of neutrophils at infection sites

Question 5

Chediak Higashi Syndrome

Answer 5

Macrophage defect
Defect; Defect in lysosomal trafficking regulator gene (LYST), Microtubule dysfuction in phagosome-lysosome fusion
- AR
Presentation
- Recurrent pyogenic infections by staph and strep,
- partial albinism,
- peripheral neuropathy, progressive neurodegeneration
- infiltrative lymphohistiocytosis
Findings
- Giant granules in granulocytes and platelets
- Mild coagulation defects

Question 6

Chronic Granulomatous Disease

Answer 6

Macrophage defect
Defect: Defect of NADPH oxidase –> dec reactive oxygen species (superoxide) and dec. respiratory burst in neutrophilss, X-linked most common
Presentation
“Need PLACESS”
Nocardia, pseudomonas, listeria, aspergillus, Candida, Ecoli, S.aureus, Serratia
Findings: Abnormal Dihydrorhodamine test, Nitroblue tetrazolium dye reduction test is negative

Question 7

Severe Combined Immunodeficiency

Answer 7

B and T cell disorder
Defect: (multiple)
1. Defective IL-2R gamma chain (x-linked)
2. defective adenosine deaminase (autosomal recessive)
Presentation
Failure to thrive, diarrhea, thrush
Recurrent viral, bacterial, fungal, and protozoal
Findings:
- Dec. T cell receptor excision circle (TRECs)
- Absence of thymus shadow, germinal centers, and T cells