Immunodeficiencies Flashcards
what are the 2 types of immunodeficiences
- primary/congenital
- secondary/aquired
what type of immunodeficiency are usually from a genetic defect
primary immunodeficiency
How does a primary immunodeficiency in differ b/w innate and adaptive immunity ?
- only affects an “aspect” of innate immunity
- complete deletion/abscence of an arm of the adaptive immunity
what is the principle consequence of an immunodeficiency
increased susceptibility to infection
a patient would be more susceptible to a viral infection if they had a deficient _______ immunity
cell mediated (No T cells)
a patient would be more susceptible to a bacterial infection if the had a deficient _______ immunity
humoral (No B cells)
What are the characteristics of immunodeficiency X linked Agammaglobulinemia (XLA)
- All Ab isotypes are low
- B cells absent
- pre-B cells reduced
what is the outcome for a patient with X linked agammaglobulinemia (XLA)
Boy will live for 6-9 months by virtue of their mothers IgG isotype that crossed placenta during birth. Once those die off boy will get infections and die.
What is the actual cause of B cells to be absent and pre-B cells to be reduced in XLA
Loss of function of Bruton Tyrosine Kinase (BK deficiency), which is needed for pre-B cell maturation
What are the characteristics of X linked immunodeficiency w/ hyper-IgM
- High amounts of IgM
- Low amounts of other isotypes (IgG, IgA, IgE)
- Cant perform isotype switching*
what is the only immunoglobulin that can cross the placenta
IgG
what is the first immunoglobulin to be secreted in response to infection
IgM (pentameric)
What are the characteristics of immunodeficiency X linked Agammaglobulinemia (XLA)
Humoral immunodeficiency
- All Ab isotypes are low
- B cells absent
- pre-B cells reduced
What is the specific underlying cause of why patients w/ X linked immunodeficiency hyper-IgM can not perform isotype switching ?
Loss of CD40L in helper T cells = cant signal B cells to perform isotype switching = only produce IgM
What type of immunodeficiency is more severe, a deficient humoral immunity or deficient cell mediated immunity ?
deficient cell mediated (No T cells)
-usually more severe b/c help to signal B cells
what is the difference in treatment b/w humoral and cell mediated immunodeficiencies
humoral immunodeficiency - routine prophylactic treatment w/ gamma-globulin therapy
cell mediated - Little to NO treatments
T/F it is rare for a patients with a defect in T cell function to survive beyond infancy
True
What are the characteristics of DiGeorge’s syndrome ?
Cell mediated immunodeficiency
- defect in chromosome 22
- thymus does not develop so T cells cant mature
- patients die from infections in infancy
What are the characteristics of X linked Recessive Severe Combined Immunodeficiency disease (X linked SCID)
- Profound deficiencies in B and T cells
- Cant make functional receptors
- **This is the disease w/ the boy in a bubble **
what is the most severe primary immunodeficiency
X linked SCID
What are the current 2 strategies for treatment of immunodeficiencies ?
1 - minimize and control infections
2 - replace defective part of immune system via adoptive transfer or transplantation
What is the difference in how B cells are affected b/w DiGeorge’s syndrome and X linked SCID
- Digeorge’s syndrome - B cells are high in percentage and only affected to the extent of having no Helper T cell
- X linked SCID has elevated percentage of B cells, BUT they are not functional as cant produce immunoglobulins
What is the most common secondary or acquired immunodeficiency ?
HIV
how does the secondary immunodeficiency HIV affect humans
Virus enters the body and hijacks immune system, specifically the T cells
destroys helper T cells
