Immunodeficiency Flashcards
(36 cards)
difference between primary and secondary immunodeficiencies
primary- congenital- rare
secondary- acquired- common
what are the 4 components of the immune response that can be targeted in immunodeficiency
- t cells
- b cells
- phagocytes
- complement
what types of infections are typical for each component of the immune system?
t-cell deficiencies lead to intracellular infections of mycobacteria, viruses, and fungi
all other deficiencies lead to extracellular bacterial infections
name some warning signs of primary immunodeficiencies
- recurrent ear/sinus infections, pneumonia, or other infections w/in a year
- poor response to antibiotics
- recurrent deep skin lesions
- failure to thrive
- family history
describe methods to detect B-cell deficiencies
- serum immunoelectrophoresis
- quantification of serum Igs
- quantification of B cells via flow cytommetry
- dectection of specific Abs (Schick test)
- induction of in-vivo b-lymphocyte differentiation
- lymph node biopsy
describe methods to detect t-cell deficiencies
- DTH to common atigens
- total lymphocyte count
- quantification and classification using Ab/FACS
- proliferation in response to alloantigens- mixed lymphocyte reaction
- in vitro analysis of cytokine production
describe evaluation of phagocyte function
- total granulocyte/monocyte count
- chemotaxis assay
- assay for phagocytosis of opsinized particles
- test for superoxide generation using NBT
- assay for cytokines/response to cytokines
- antigen processing/ presentation
describe evaluation of complement system
- total hemolytic complement assay- CH50
- immunoassay for individual components
- neutrophil chemotaxis w/ complement subunits
how might B cells develop deficiencies if nothing is wrong with them?
if helper t cells are damaged and cannot facilitate class switching, b cell repsonses will be impaired
brutons disease
b cells fail to develop congenitally
XLA
x linked disease where b cells fail to develop d/t a defective gene encoding btk, which is an important signaler in the progression of b cell precursors
hyper-Igm syndrome
increased IgM but defective coding for either CD40 or CD40L means no helper t cell interaction for class switching
common variable IgG/IgA immunodeficiencies
low IgG or IgA w/ impaired Ab production in response to infection/vaccine
what is the most common primary immunodeficiency?
IgA- leads to increased upper respiratory infections
why are deficiencies where only cell mediated immunity is affected rare?
b/c t cells are so important in activating b cells, if you impair t cells you impair b cells
digeorge syndrome
d/t to an absent or very small thymus, w/ severity depending on the amount of thymus present
bare lymphocyte syndrome
defects in genes needed for MHC class 2 lead to a lack of CD4 cells and severe SCID
TAP1 or TAP2
defects in these genes lead to a lack of MHC class 1 and no CD8 cells
wiskott-aldrich syndrome
mutations in WAS protein result in an impaired T cell activation
ataxia telangiectasia
caused by mutations that damage ATM protein important for DNA repair, causing impaired lymphocyte development
define SCID and some its most common causes
severe combined immunodeficiency- affects both T and B cells
- stem cell defects in the y chain common to many cytokine receptors
- ADA enzyme leading to toxicity of purine metabolite buildup which inhibit DNA synthesis
- defects in enzymes involved in recombination, thus cannot produce functional Igs or TCRs
what are the 2 types of phagocyte deficiencies?
intrinsic- related to the inherent properties of the phagocyte, such as differentiation, chemotaxis, or intracellular killing
extrinsic- deficiency in Ab or C, immunosuppression
cyclic neutropenia
pts have a low neutrophil count fo 3-6 days in a 21 day cycle
leukocyte adhesion deficiency
leukocytes have difficulty adhering to endothelium at sites of inflammation
