Flashcards in Immunodeficiency Deck (32):
When should immune evaluation be considered?
two or more invasive bacterial infections, persistent or recurrent sinopulmonary infections, unusual etiologic agents or unusual severity of common infection
What are some physical examination findings that may indicate immunodeficiency?
less growth/development, enlarged/absent tonsils, nodes, liver, spleen, thrush, rash
What are the four limbs of the immune system?
cellular immunity, humoral immunity, complement, phagocytes
What is the most common immunodeficiency?
selective IgA deficiency, can be asymptomatic
What is severe combined immunodeficiency? What is the prognosis? (SCID)
no T cells or B cells, early death without BM transplant
What causes SCID?
IL-2 gamma chain defect
Why does a IL-2 gamma chain defect cause immunodeficiency?
IL-2 gamma chain is the critical signal transduction component of the IL-2 receptor
What signals can no longer be processed if there is an IL-2 gamma chain defect?
B-cell maturation, NK cell development, hematopoises, T-cell development, class-switch, peripheral T cell homeostasis signals
How can you diagnose SCID?
lymphopenia, analysis of lymphocyte proliferation in response to mitogens, non-self HLA antigens in mixed lymphocyte culture or specific antigens (would have to know hx of what they should be responsive to), thrush
What are mitogens? What are 3 examples?
plant lectins that bind to sugars on cell surfaces, crosslink them, and stimulate T cells and B cells
-PHA, conA, pokeweed
What occurs in mixed lymphocyte culture?
Look at proliferation of self lymphocytes in response to irradiated stimulating lymphocytes (that will not proliferate), tests reaction to non-self HLA
Why is it important to know the history of patient exposures for lymphocyte proliferation analysis?
for testing specific antigens, need to know if they should be responsive to it
What are treatments for SCID?
aggressive Abx and antivirals, BM transplant, replacement Ig (half-life of 2-3 weeks)
What is the most common presentation of humoral immunodeficiency?
respiratory infection or unusual enteric infection from lack of IgA or increased severity of a usually not severe infection
What causes X-linked agammaglobulinemia?
absence of B-cells due to mutation in Bruton's tyrosine kinase, cannot mature
What does a CD40L deficiency result in for humoral immunity? cell-mediated immunity?
hypo-IgG/IgA with hyper-IgM, can't class switch because need CD40L-CD40 interaction with T cell for IL-4 stimulation of B cell, no germinal centers in lymph nodes, macrophages will not be activated
What type of infections is there an increased risk for with humoral immunodeficiency?
encapsulated pathogens, esp. pneumococci, chronic enterovirus meningoencephalitis
What type of immunodeficiency leads to increased risk for lymphoma? Why?
humoral, lack of T cell and B cell interactions leads to tumors
What Ab deficiency has a defect in producing Ab to polysaccharide antigens?
What would cause increased susceptibility to Neisseria meningitis or gonorrhea?
How can you treat complement deficiency?
vaccinate against meningococcus since B cells are normal and will produce antibodys, treat pts with antibiotic prophylaxis
What indicates a phagocyte deficiency?
fungal infection, unusual suppurative infection, chronic granulomatous disease
What is the most common qualitative neutrophil defect called? What is it?
chronic granulomatous disease, eats the bacteria but isn't generating an oxidative burst so it forms a granuloma, need activated macrophage to kill bacteria
What is NBT reduction assay?
when put the clear solution on activated neutrophils it turns into blue crystals
if it stays clear the neutrophils aren't work right
Where is the risk for infection higher with phagocyte deficiency, in catalase positive or catalase negative bacteria?
catalase positive- they get rid of the peroxide they generate and rely on phagocyte to give oxidative burst
catalase negative bacteria make peroxide that is not broken down further so it can build up in phagosome and help kill bacteria over time
How do you treat phagocyte deficiency?
antibiotic prophylaxis, early identification and treatment of infections, IFNgamma to activate macrophages
What is DiGeorge's syndrome?
abnormal embryonic development of the 3rd and 4th pharyngeal pouches, congenital thymic hypoplasia/aplasia (no maturation of Tcells), and hypoparathyroidism (abnormal calcium levels)
What are infection risks for cellular immunodeficient patients?
viral and fungal diseases
Why do you use irradiated blood products for cellular immunodeficient patients?
T cells can come in on blood products and attack host tissues, irradiate the blood product to kill those T cells
Why is there some improvement in cellular immune function over time?
more extrathymic maturation of T cells as you age
What cells do HIV target?
CD4+ T cells, macrophages (but not killed)