Selective B Cell Immunodeficiency Flashcards

1
Q

What is agammaglobulinemia/X linked Btk deficiency?

A

T+B-NK+
Absent Ig levels
X linked mutation in Btk causing early B cell development arrest at the pre-B cell stage
Leads to absence of circulating B cells
Also results in defective rearrangement of heavy chain genes

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2
Q

Which infections are most common in those with agammaglobulinemia and X linked Btk deficiency?

A

Recurrent bacterial infections

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3
Q

What vaccines should be avoided for those with agammaglobulinemia and X linked Btk deficiency?

A

No live vaccines

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4
Q

Which B cell immunodeficiencies can be treated with HSCT?

A

Agammaglobulinemia, X linked Btk deficiency and common variable immune deficiency (CVID)

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5
Q

Which B cell immunodeficiencies can be treated symptomatically?

A

IgA and IgG deficiencies, hyper IgM and transient hypogammaglobulinemia of infancy

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6
Q

Which B cell immunodeficiencies have no vaccine restrictions?

A

IgA and IgG subclass deficiencies

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7
Q

Polio vaccine is not recommended for which B cell immunodeficiencies?

A

Hyper IgM, transient hypogammaglobulinemia of infancy and CVID

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8
Q

What is IgG deficiency?

A

T+B+NK+
IgG absent, normal everything else
Caused by defects in several genes
Mostly asymptomatic but can present with recurrent bacterial infections
Low IgG2 = poor response to polysaccharide Ags in children

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9
Q

What is IgA deficiency?

A

T+B+NK+
Absent IgA, normal everything else
Caused by mutation of terminal differentiation
Mostly asymptomatic but can present with recurrent bacterial infections
Related to autoimmune disease and allergies

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10
Q

Why are 50% of IgA deficiency pts asymptomatic?

A

Due to IgM translocation across mucosal epithelium

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11
Q

What is hyper IgM syndrome?

A

T+B+NK+
High IgM, low everything else
Impaired class switching and somatic hypermutation
Peripheral B cells are normal, but no CD27+ memory B cells
Increased susceptibility to bacterial infections
Ex. X linked CD40 (males) is 2/3 of all cases and autosomal CD40 deficiency (males and females) is 1/3 of all cases

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12
Q

What is transient hypogammaglobulinemia of infancy?

A

T+B-/+NK+
Normal IgM, low IgG and IgA
Intrinsic Ig production delayed for up to 36 mo causing increased susceptibility to sinopulmonary infections
Ig concentrations normalize between 2-4 y/o

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13
Q

What is common variable immune deficiency (CVID)?

A

T+B-/+NK+
Low IgG and IgA, sometimes low IgM
Characterized by defect in Ab production associated w/ hypogammaglobulinemia
Dx = hx of pyogenic sinopulmonary infections (at 20-30 y/o)
Leads to recurrent infections, autoimmune disease and lymphomas

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14
Q

Which two deficiencies lead to opportunistic encapsulated infections?

A

Hyper IgM and transient hypogammaglobulinemia

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