Immunology

Question 1

If your NK cell function was compromised, what pathogens would you be at risk for infection from?

Answer 1

Viruses (esp DNA viruses)

Question 2

Decreased CD3/CD4 and CD3/CD8 T cells increases your risk of what type of infection?

Answer 2

Viruses
Pneumocystis
Fungi

Question 3

Decreased B cells would increase your risk of what type of infection?

Answer 3

bacteria (esp encapsulated)

Question 4

Decreased neutrophils increases your risk of what types of infections?

Answer 4

bacterial

fungal

Question 5

list two risk factors for infection pre-engraftment (day 0-30) and what infections they are at risk for

Answer 5

profound neutropenia and a CVL

risk of bacterial infection, candida, aspergillus, HSV, respiratory viruses

Question 6

list risk factors for infection post-engraftment (day 30-100) and what infections they are at risk for

Answer 6

lymphopenia (esp CD4 t cells), on t cell suppressive meds, CVL
aGVHD

risk of: bacterial infections, aspergillus, CMV, respiratory viruses, EBV reactivation, PCP, toxoplasmosis

Question 7

list risk factors for infection post-engraftment (late > 100) and what infections they are at risk for

Answer 7

lymphopenia (CD4), t cell suppressive meds, cGVHD, poor Ig production

risk of: encapsulated organisms (esp if functional asplenia), aspergillus, VZV, CMV, EBV, PCP, toxo, resp viruses

Question 8

bacterial infections in immunocompromised hosts are:

Answer 8

from endogenous flora (gram neg rods from gut, gram positive cocci, anaerobes)

Question 9

high-dose cytarabine is associated with what infectious complication

Answer 9

alpha-hemolytic strep (s.mitis, s. sanguis) with ARDS and rapidly evolving sepsis syndrome

Question 10

spleen is the site of what types of b cells?

Answer 10

marginal zone b cells - respond to polysaccharide antigens

Question 11

if asplenic, what vaccines do you need?

Answer 11

pneumococcus, HiB, meningococcus

Question 12

risk factors for fungal infections

Answer 12

prolonged neutropenia

CD4 lymphopenia

Question 13

prophylaxis for candidiasis?

Answer 13

fluconazole (azole) or caspofungin (echinocandin)

Question 14

risk factors for pneumocystis jirovecii

Answer 14

CD4 count < 200
prolonged neutropenia
immunocompromised
steroid treatment

Question 15

alternatives to septra?

Answer 15

atovaquone
dapsone
pentamidine (IV, inh)
clindamycin plus primaquine

Question 16

treatment for CMV infection

Answer 16

ganciclovir
valganciclovir
foscarnet
cidofovir

Question 17

treatment of HSV

Answer 17

acyclovir

foscarnet

Question 18

how long after exposure to HSV can you administer VZIG?

Answer 18

up to 96 hrs post

Question 19

treatment in immunocompromised host for HSV?

Answer 19

acyclovir

Question 20

what cells are considered lymphocytes? what are their characteristic cell surface markers?

Answer 20

CD16/56 - NK cell (innate imm)
CD4 - helper T cell
CD8 - killer T cell
CD19 - B-cell

Question 21

what MHC class do CD4 t cells recognize?

Answer 21

MHC class II

Question 22

function of CD4 t cells

Answer 22

class switching of b cells

Question 23

antigens characterizing pre-B cells

Answer 23

CD 19
CD 10
loss of CD 34
(no CD20 until later)

Question 24

testing function of t cells

Answer 24

proliferation to mitogens (phytohemagglutinin, PWM, conA)

proliferation to antigen (candida)

Question 25

testing function of b cells

Answer 25

measuring immunoglobulins
measuring specific antibodies (ie, vaccine titers, blood group)
antibody production requires intact t cell function

Question 26

which immunoglobulin is transfered via placenta

Answer 26

IgG (monomeric - small)

Question 27

physiologic nadir in immunoglobulin (IgG) levels

Answer 27

2-6 months

Question 28

what is absent in SCID?

Answer 28

t cells

Question 29

condition without b cells?

Answer 29

x-linked agammaglobulinemia

Question 30

failure of t cell development

Answer 30

SCID

Question 31

how to diagnose scid?

Answer 31

check lymphocyte count
check lymphocyte subsets
lymphocyte proliferation studies (low proliferation to mitogens)

Question 32

T-B+ SCID caused by what mutations

Answer 32

cytokine common gamma chain
JAK3
IL-7 receptor alpha chain

Question 33

lack of what receptor leads to absence of T cells

Answer 33

IL-7R

Question 34

lack of what receptor leads to absence of NK cells

Answer 34

IL-15R

Question 35

how can a baby with SCID have t-cells?

Answer 35

from maternal engraftment

Question 36

x-linked agammaglobulinemia - gene involved?

Answer 36

bruton’s tyrosine kinase (BTK) gene

Question 37

X linked agammaglobulinemia - what is pathophysiology?

Answer 37

mutation in BTK gene resulting in arrest of b-cell development at pre-B stage - absence of peripheral b cells

Question 38

how does XLA present?

Answer 38

the boys have maternal IgG so don’t present until 6-9 months with infections

Question 39

what infections are boys with XLA at risk for?

Answer 39

chronic enteroviral meningoencephalitis - avoid live vaccines

Question 40

diagnosis of XLA

Answer 40

absence of CD19 cells, low immunoglobulins

Question 41

WAS

Answer 41

x-linked
deficiency of WASP protein
triad: immunodeficiency, eczema, small platelets (MPV 4-5)
may also have high IgE

Question 42

WAS defect

Answer 42

combined T and B defect
numbers may be normal
function abnormal - lacking carbohydrate responses (isohemagglutinins, pneumovax)