2.4.2 Antibody Disorders (CVID and IgA Deficiency) Flashcards
What are some things that may make you suspect immunodeficiency?
§Family history
§Failure to thrive
§Need for multiple courses or IV antibiotics
§3+ sinusitis in 1 year
§2+ pneumonias in 1 decade
§4+ otitis in 1 year (depending on the age)
§2+ sepsis or meningitis
§Resistant candidiasis, abscesses, opportunistic organism, non-healing wounds
§Chronic diarrhea
§Persistent lymphopenia
§Unexplained autoimmunity
§Hypocalcemia
§Congenital heart defects
§Absence of thymic shadow on CXR
§Delayed umbilical cord detachment (30 days)
§Complication from live viral vaccination
What branch of primary immune deficiencies is most common?
Humoral immunity (B cell) deficiencies
Is primary or secondary immune deficiency more common?
Secondary
What are some causes of secondary immune deficiencies?
§Underlying disease (HIV/AIDS, DM, malignancy)
§Medications (immunosuppressives)
§Injury or Surgery
§Prematurity
§Unhealthy mother
Describe the process of B cell differentiation.
How do B cells produce different kinds of antibodies?
Class switch
Describe the process in which T cells-B cells interact with one another.
Through which process do B cells class switch? What enzyme plays an important role in this process?
Loop out DNA (IgM -> IgG -> IgE/IgA)
Enzyme: Activation induced cytidine deaminase (AID)
Which Ig molecule can cross the placenta?
IgG
Which Ig molecule is important in lining mucosa?
IgA
What is the specificity of IgE?
Binds mast cells and basophils on Fc(epsilon)RI
What are 3 different ways that B cells can go awry?
B Cell Lymphoma: too many B cells
Autoimmune B cells: attack the host
Humoral immunodeficiency: not enough Ab or nonfunctional Ab
What are some important labs when assessing a potential immunodeficiency?
CBC w/ diff, Sed Rate, Ig Levels, Ab level following vaccination, CH50 and AH50, Flow cytometry, TRECs, Leukocyte adhesion defect test, Isoagglutinins
Based on this lab, what is the patient’s possible deficiency?
§CBC with differential is normal
§ESR(sed rate): 35 mm/hr (normal <20)
§IgA: 6 mg/dL (70-390, absent if <7)
§IgM: 88 mg/dL (38-328)
§IgG: 849 mg/dL(767-1590)
IgA deficiency
Give some examples of humoral deficiencies?
§Selective IgA deficiency
§Severe combined immunodeficiency (SCID)
§Bruton’s agammaglobulinemia
§Common variable immunodeficiency (CVID)
§IgG subclass deficiency
§Selective antibody deficiency with normal immunoglobulins (SADNI)