Immunodeficiencies

Question 1

what are the 2 types of immunodeficiences

Answer 1

• primary/congenital

- secondary/aquired

Question 2

what type of immunodeficiency are usually from a genetic defect

Answer 2

primary immunodeficiency

Question 3

How does a primary immunodeficiency in differ b/w innate and adaptive immunity ?

Answer 3

• only affects an “aspect” of innate immunity

- complete deletion/abscence of an arm of the adaptive immunity

Question 4

what is the principle consequence of an immunodeficiency

Answer 4

increased susceptibility to infection

Question 5

a patient would be more susceptible to a viral infection if they had a deficient _______ immunity

Answer 5

cell mediated (No T cells)

Question 6

a patient would be more susceptible to a bacterial infection if the had a deficient _______ immunity

Answer 6

humoral (No B cells)

Question 7

What are the characteristics of immunodeficiency X linked Agammaglobulinemia (XLA)

Answer 7

• All Ab isotypes are low
• B cells absent
• pre-B cells reduced

Question 8

what is the outcome for a patient with X linked agammaglobulinemia (XLA)

Answer 8

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.

Question 9

What is the actual cause of B cells to be absent and pre-B cells to be reduced in XLA

Answer 9

Loss of function of Bruton Tyrosine Kinase (BK deficiency), which is needed for pre-B cell maturation

Question 10

What are the characteristics of X linked immunodeficiency w/ hyper-IgM

Answer 10

• High amounts of IgM
• Low amounts of other isotypes (IgG, IgA, IgE)
• Cant perform isotype switching*

Question 11

what is the only immunoglobulin that can cross the placenta

Answer 11

IgG

Question 12

what is the first immunoglobulin to be secreted in response to infection

Answer 12

IgM (pentameric)

Question 13

What are the characteristics of immunodeficiency X linked Agammaglobulinemia (XLA)

Answer 13

Humoral immunodeficiency

• All Ab isotypes are low
• B cells absent
• pre-B cells reduced

Question 14

What is the specific underlying cause of why patients w/ X linked immunodeficiency hyper-IgM can not perform isotype switching ?

Answer 14

Loss of CD40L in helper T cells = cant signal B cells to perform isotype switching = only produce IgM

Question 15

What type of immunodeficiency is more severe, a deficient humoral immunity or deficient cell mediated immunity ?

Answer 15

deficient cell mediated (No T cells)

-usually more severe b/c help to signal B cells

Question 16

what is the difference in treatment b/w humoral and cell mediated immunodeficiencies

Answer 16

humoral immunodeficiency - routine prophylactic treatment w/ gamma-globulin therapy
cell mediated - Little to NO treatments

Question 17

T/F it is rare for a patients with a defect in T cell function to survive beyond infancy

Answer 17

True

Question 18

What are the characteristics of DiGeorge’s syndrome ?

Answer 18

Cell mediated immunodeficiency

• defect in chromosome 22
• thymus does not develop so T cells cant mature
• patients die from infections in infancy

Question 19

What are the characteristics of X linked Recessive Severe Combined Immunodeficiency disease (X linked SCID)

Answer 19

• Profound deficiencies in B and T cells
• Cant make functional receptors
• **This is the disease w/ the boy in a bubble **

Question 20

what is the most severe primary immunodeficiency

Answer 20

X linked SCID

Question 21

What are the current 2 strategies for treatment of immunodeficiencies ?

Answer 21

1 - minimize and control infections

2 - replace defective part of immune system via adoptive transfer or transplantation

Question 22

What is the difference in how B cells are affected b/w DiGeorge’s syndrome and X linked SCID

Answer 22

• 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

Question 23

What is the most common secondary or acquired immunodeficiency ?

Answer 23

HIV

Question 24

how does the secondary immunodeficiency HIV affect humans

Answer 24

Virus enters the body and hijacks immune system, specifically the T cells
destroys helper T cells