IR to infectious disease

Question 1

Which two cell types initially respond to intracellular bacterial pathogens during the innate IR?

Answer 1

Neutrophils & macrophage

Question 2

Which cells, when stimulated, release IL12 (depends on the pathogen), which immune cell is recruited during the innate IR to assist in the killing of the intracellular bacteria?

Answer 2

a. Neutrophils & macrophages

b. NK cells (release IFN-gamma => kill internal microbe)

Question 3

During the adaptive IR to an intracellular pathogen, macrophages engulfing the microbe can be assisted by which type of lymphoid cell? Which cytokine is involved?

Answer 3

a. T helper cell

b. IFN-gamma

Question 4

If an intracellular bacterial pathogen escapes the phagolysosome of the macrophage during the adaptive IR, which immune cell can respond?
What happens?

Answer 4

a. Cytotoxic T cell
b. Cytotoxic T cell is activated w/ Th1 & APC bind to infected cells => release porins & enzymes = kill cell & microbe

Question 5

List the principle immune cells involved in the combined IR responses to fungal infection?

Answer 5

• Netutrophils & macrophages (innate)

- Th 17 (adaptive)

Question 6

Which cell type is responsible for eliminating virally infected host cells during the innate IR?

Answer 6

NK cell : detect reduction of MHC 1 presentation

Question 7

List 3 biological roles of type 1 interferons on non-lymphoid cells during the innate IR to viruses?

Answer 7

• inhibit viral protein synthesis in infected cells
• Stimulates production of enzymes > degrade viral RNA
• inhibit viral gene expression & viron assembly

Question 8

Which cell type is associated with killing virally infected cells as part of the adaptive IR?

Answer 8

a. CD8 cytotoxic T cells

Question 9

Which T helper response is important in killing virally infected cells in adaptive IR?

Answer 9

Th1

Question 10

What primary role do antibodies play in adaptive immunity to a virus and which immune cell is most likely to respond to an opsonised infected cell?

Answer 10

a. neutralisation > prevent virus from attaching on host cell (Th1 = IgG1, IgG3; Th2 = IgA)
b. NK cells respond to IgG (from Th1)

Question 11

In respect of viruses, what is antigenic shift and drift?

Answer 11

Drift: Slow bc requires accumulation of mutations to change surface Ag
Shift: quick bc genetic reassortment of genes => new virus - antigenically distinct from precursors

Question 12

List the three mechanisms by which virally infected cells can be eliminated? (one is innate and two are adaptive)

Answer 12

1. NK cells due to reduced expression of MHC 1 (innate)
2. ADCC: IgG bind to viral Ag on infected cell => NK cells target & kill (adaptive)
3. Cytotoxic T cell detect Ag expressed on MHC 1 & kill (adaptive)

Question 13

Why does the secondary immune response generally occur rapidly with higher levels of IgG antibody compared to the primary immune response?

Answer 13

bc 2º IR has memory cells. When stimulated by same Ag it rapidly proliferates into B cells & release IgG.
1º IR doesn’t have memory cells bc only encountered Ag for the first time

Question 14

Following vaccination and assuming that an appropriate and adequate immune response is stimulated, draw and label a diagram that depicts the primary Aby immune response as well as the secondary Aby immune response after re-exposure to that same antigen?

Answer 14

1º: IgM produced 1st -> IgG [ ] slightly above IgM

2º: IgM produced 1st & less [ ] as 1º -> IgG rapidly produced & @ higher [ ] than 1º