Immunology

Question 1

Common variable immune deficiency

Answer 1

• low IgG and IgA; normal/low IgM

* both males and females affected equally

Question 2

IgA deficiency

Answer 2

• low IgA; normal IgG and IgM

* diagnosis- often remain asymptomatic

Question 3

Hyper IgM syndromes

Answer 3

• high IgM; low IgG and IgA
• X-linked HIGM is due to mutations in CD40L gene: 2/3 cases
• Autosomal CD40 deficiency: 1/3 cases
• have increased susceptibility to bacterial infections
• low memory B cells

Question 4

Isolated IgG subclass deficiency

Answer 4

*total IgG, IgM, IgA, and IgE are normal

Question 5

Transient hypogammaglobulinemia of infancy

Answer 5

• low IgA and IgG; IgM can be normal

* in the majority of patients, Ig concentrations normalize between 2-4 years of age

Question 6

Wiskott-Aldrich syndrome

Answer 6

• low IgM; IgG normal; IgA and IgE elevated
• x-linked
• mutation in WASP- expression limited to cells of hematopoietic lineage
• clinical manifestations: thrombocytopenia, small platelets, multiple bruises, platelet dysfunction, eczema, susceptibility to infections

Question 7

common gamma chain deficiency

Answer 7

• x-linked
• T-B+NK-
• clinical signs: opportunistic fungal infections; chronic diarrhea; skin, mouth, and throat lesion

Question 8

Adenosine deaminase deficiency

Answer 8

• autosomal recessive
• T-B-NK-
• leads to an accumulation of toxic metabolic by-products

Question 9

Deficiency of Jak3

Answer 9

• autosomal recessive
• causes defect in IL-2 receptor signaling
• T-B+NK-

Question 10

DiGeorge syndrome

Answer 10

• classical example of T-cell deficiency
• key biochemical feature is hypocalcemia
• complete or partial failure or development of thymus
• susceptible to opportunistic infections

Question 11

Severe chronic neutropenia

Answer 11

• mutation in the neutrophil elastase gene (ELA2)

* defect in life cycle of neutrophils

Question 12

Chronic granulomatous disease

Answer 12

• tendency to form granulomas
• most frequent phagocytic primary immunodeficiency
• enzymatic deficiency in NADPH oxidase in phagocytes

Question 13

G6PD deficiency

Answer 13

• x-linked
• associated with anemia
• lack substrate for NADPH
• formation of granulomas

Question 14

Chediak-Higashi syndrome

Answer 14

• partial albinism
• abnormal giant granules in neutrophils
• no NK activity
• prone to recurrent pyogenic infections
• a biphasic immunodeficiency
• giant azurophilic cytoplasmic inclusions in blood cells
• impaired phagocytosis due to inability of endosomes to fuse with lysosomes

Question 15

Leukocyte adhesion deficiency

Answer 15

• assessment of CD11 and CD18
• neutrophils lack functional integrins so they do not bind to intercellular adhesion molecules on endothelial cells
• clinical manifestations: delayed detachment of umbilical cord, slow wound healing, severe bacterial infections, failure to form pus

Question 16

X-linked agammaglobulinemia

Answer 16

• low/absent IgG, IgA, IgM
• the reticuloendothelial and lymphoid organs in which B cells proliferate, differentiate and stored are poorly developed or absent
• mutations in Btk gene