Selective B Cell Immunodeficiency Flashcards
What is agammaglobulinemia/X linked Btk deficiency?
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
Which infections are most common in those with agammaglobulinemia and X linked Btk deficiency?
Recurrent bacterial infections
What vaccines should be avoided for those with agammaglobulinemia and X linked Btk deficiency?
No live vaccines
Which B cell immunodeficiencies can be treated with HSCT?
Agammaglobulinemia, X linked Btk deficiency and common variable immune deficiency (CVID)
Which B cell immunodeficiencies can be treated symptomatically?
IgA and IgG deficiencies, hyper IgM and transient hypogammaglobulinemia of infancy
Which B cell immunodeficiencies have no vaccine restrictions?
IgA and IgG subclass deficiencies
Polio vaccine is not recommended for which B cell immunodeficiencies?
Hyper IgM, transient hypogammaglobulinemia of infancy and CVID
What is IgG deficiency?
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
What is IgA deficiency?
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
Why are 50% of IgA deficiency pts asymptomatic?
Due to IgM translocation across mucosal epithelium
What is hyper IgM syndrome?
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
What is transient hypogammaglobulinemia of infancy?
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
What is common variable immune deficiency (CVID)?
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
Which two deficiencies lead to opportunistic encapsulated infections?
Hyper IgM and transient hypogammaglobulinemia