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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?

selective IgA


What would cause increased susceptibility to Neisseria meningitis or gonorrhea?

complement immunodeficiency


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)


What malignancies are associated with HIV?

Kaposi's sarcoma, lymphoma, squamous cell carcinoma