Ch 10 Book Questions

Question 1

A major function of TH1 cells is to activate macrophages. Which molecules expressed by TH1 cells are essential for this function?

a. IL-1 and TNF
b. CD8 and Fas ligand
c. IL-17 and NO
d. Interferon γ and CD40 ligand
e. IL-4 and ICOS

Answer 1

d. Interferon γ and CD40 ligand

TH1 cells activate macrophages via secreted interferon γ and membrane CD40 ligand, which bind respectively to interferon γ receptors and CD40 on the macrophages. TH1 cells express CD4 and not CD8. Although TH1 cells express Fas ligand, this molecule does not activate macrophages, but rather binds to Fas on various cell types and induces apoptotic cell death. IL-17 and NO are not made by TH1 cells. IL-4 is not made by TH1 cells, and ICOS does not activate macrophages.

Question 2

Activated macrophages perform all of the following functions EXCEPT:

a. Inhibition of fibroblast proliferation and angiogenesis within damaged tissues
b. Production of lysosomal enzymes and reactive oxygen species that kill phagocytosed microbes
c. Presentation of antigen to helper T cells
d. Secretion of inflammatory cytokines such as tumor necrosis factor and interleukin-1
e. Production of nitric oxide, which helps kill microorganisms

Answer 2

a. Inhibition of fibroblast proliferation and angiogenesis within damaged tissues

Activated macrophages, through the secretion of growth factors, promote fibroblast proliferation and angiogenesis which help repair damaged tissues.

Question 3

Which of the following is one way a cytokine made by TH2 cells contributes to atopic disease (allergy)?

a. IL-17 stimulates TNF production by macrophages
b. IL-5 activates eosinophils
c. IL-13 activates macrophages to produce nitric oxide
d. IL-4 induces B cell class switching to IgA
e. IL-22 causes mast cell degranulation

Answer 3

b. IL-5 activates eosinophils

Atopic diseases often involve eosinophil activation and the release of pro-inflammatory and tissue damaging granule contents, such as major basic protein. TH2 cells underlie these events because they produce IL-5. IL-17and IL-22 are not made by TH2 cells. IL-13 does not activate macrophages to produce nitric oxide. IL-4 does induces B cell class switching to IgE not IgA

Question 4

Alternative macrophage activation is characterized by which one of the following?

a. Reactive oxygen species (ROS) generation
b. IL-1 production
c. Microbial killing
d. IL-10 and TGFβ secretion
e. IL-4 and IL-13 secretion

Answer 4

d. IL-10 and TGFβ secretion

Alternatively activated macrophages secrete the anti-inflammatory cytokines IL-10 and TGFβ. They also enhance angiogenesis and fibrosis. ROS generation, IL-1, and microbial killing are characteristic of classically activated macrophages. IL-4 and IL-13 are cytokines made by TH2 cells, which induce alternative macrophage activation.

Question 5

Which type of T cell is most likely to promote acute neutrophillic inflammatory responses that defend against extracellular bacteria and fungi?

a. TH1
b. TH2
c. TH17
d. CTL
e. T follicular helper

Answer 5

c. TH17

IL-17 produced by TH17 cells induces many cell types to make chemokines such as IL-8, and cytokines such as IL-1 and TNF, all of which enhance neutrophil recruitment into tissues. TH1 cells and CTLs, which secrete IFNγ, are more typically associated with chronic inflammatory infiltrates rich in activated macrophages, and TH2 cells are associated with eosinophil-rich inflammation. T follicular helper cells do not promote inflammatory responses, but rather help B cells in germinal center reactions.