Primary Immunodeficiency Flashcards
What are frequent viral and fungal infection indicative of?
T cell disorder
What are frequent bacterial infections indicative of?
B cell disorder
What are the tests for B cell function?
– Serum protein electropheresis
– Quantitation of specific Ig levels in blood
What on the CBC can indicate a T cell disorder?
Lymphocytopenia
X linked agammaglobulinemia
Mutation in a signaling tyrosine receptor that is mandatory for growth and development of B cells- specifically BLK-critical for the pre-BCR signal
What is the only pure B cell defect?
X linked agammaglobulinemia
What are the findings with X linked agammaglobulinemia?
- No Ig
- No B cells
How is X linked agammaglobulinemia treated?
Pooled IVIG
Hyper IgM syndrome
Mutation of CD40L, known as CD154, on T cells
What is the inheritance pattern of Hyper IgM syndrome?
X-linked
What are the findings with Hyper IgM syndrome and why?
• High IgM, low IgG and IgA because B cells not
prompted to isotype switch
• Switch not possible because of inability of T cells to be
activated and provide the switch cytokines
Selective IgA “deficiency”
No IgA is found - not a “true” deficiency though
What are the findings with IgA deficiency?
- IgG and IgM levels are normal
* IgA absent
What is the problem of transfusions with IgA “deficiency?”
Clinical problem is that ~10% of patients may have IgG anti-IgA antibodies. These may cause anaphylactic reactions during RBC transfusion or IVIg infusions
EBV X-linked agammaglobulinemia
• Underlying defect is a mutation in a signaling regulator of CD8 cells
• The mutation is activated by EBV infection of B cells
• If patient survives the EBV, B cell depletion by
cytotoxic T cells ensues and causes agammaglobulinemia
How does EBV X-linked agammaglobulinemia lead to death?
Ultimately die of global immune system dysfunction
because CD8 autoimmune attack on immune effector cells
Common Variable Immunodeficiency (CVID)
Fundamental defect is the inability of a B cell to differentiate to a plasma cell.

What are the findings of CVID?
- Decreased IgG, A and M levels are first abnormalities coming out from a normal childhood
- Progresses to overt T cell symptoms and then multiple autoimmune diseases, especially in the gut-PA, Celiac disease
What does CVID often culminate as?
Lymphoma
Are there B cells present in CVID?
Yes! They just cannot differentiate into plasma cells
What is the treatment for CVID?
IVIG will work until T cell defects become prominent
Thymic aplasia
There is no thymus present - deletion of 22q11.2
• Structural mutations in the 3rd and 4th branchial pouches (also called pharyngeal arches) - associated with Tetralogy of Fallot
What is often found with thyme aplasia?
Absent or deficient parathyroid glands and symptomatic
hypocalcemia
What are the findings with SCID?
Decreased or absent TRECS
