Question 1

Tumor infiltrating lymphocytes (TILs) found in a solid tumor or melanoma may indicate:&#10;A) A good prognosis due to small tumor size&#10;B) A bad prognosis due to an aggressive cancer&#10;C) A good prognosis due to a vigorous immune response&#10;D) A bad prognosis due to damage to surrounding tissue by the immune system

Accepted Answer

The presence of TILs in a solid tumor or melanoma is indicative of a vigorous immune response to the cancer. TILs are a mixture of cytotoxic CD8 and CD4 T cells, and these cells have the ability to cause apoptosis of the cancer cells. Apoptosis is an organized cell death that does not cause damage to surrounding tissue. The TIL response is not correlated to tumor size or aggressiveness of the cancer, and is often a sign of a good prognosis for the patient.

Question 2

Which molecules are required to stabilize the interaction between CD8 T cells and antigen presenting cells (APCs) that leads to activation of the CTLs?&#10;A) Fas and FasL&#10;B) CD28 and B7-1&#10;C) TNF and TNF receptor 1 (TNFRI)&#10;D) CD2 and lymphocyte function-associated antigen-1 (LFA-1)

Accepted Answer

CD28 on CD8 T cells interacts with B7-1 on APCs and acts as a second signal to activate the CTLs. Fas/FasL and TNF/TNFRI interactions lead to apoptosis of the target cells. CD2/LFA-1 interactions stabilize the reactions between CTLs and target cells.

Question 3

Which of the following is a method that viruses use to evade the immune system?&#10;A) Mutation of hemagglutinin&#10;B) Upregulation of TAP molecules&#10;C) Prevention of MHC class II expression&#10;D) Increased production of transforming growth factor-b (TGF-b)

Accepted Answer

Influenza viruses mutate surface molecules, such as hemagglutinin or neuraminidase, which renders previous B and T cell responses ineffective. This antigenic variation allows the virus to establish infection before an immune response can be mounted to the new antigens.

Question 4

What role does perforin perform in the death of target cells?&#10;A) Perforin activates caspases.&#10;B) Perforin creates a pore in the host cell.&#10;C) Perforin disrupts mitochondrial function.&#10;D) Perforin cleaves and activates granzymes.

Accepted Answer

Perforin creates a hole in either the host cell surface or in an endocytic vesicle containing the perforin inside the host cell. The pore allows granzymes to enter the host cell, either from the immunological synapse or from the endocytic vesicle. Granzymes, after being cleaved by cathepsin C, can then activate the caspase cascade to cause apoptosis, as well as disrupting other functions inside the cell.

Question 5

The main immunological defect in familial erythrophagocytic lymphohistiocytosis type 2 is:&#10;A) Inability to synthesize perforin&#10;B) Production of nonfunctional granzymes&#10;C) Inability to secrete perforin and granzymes&#10;D) Production of reduced amounts of cathepsin C

Accepted Answer

Patients with familial erythrophagocytic lymphohistiocytosis type 2 have impaired secretion of perforin and granzymes from cytotoxic lymphocytes. This impairment is accompanied by a release of large amounts of proinflammatory cytokines, which leads to infiltration of macrophages that phagocytose blood cells.

Question 6

Patients have a high risk of losing all of their teeth due which disease?&#10;A) Melanoma&#10;B) Papillion-Lef&#232;vre syndrome&#10;C) Autoimmune lymphoproliferative syndrome type 2&#10;D) Familial erythrophagocytic lymphohistiocytosis type 2

Accepted Answer

Papillion-Lefèvre syndrome is a rare autosomal recessive disorder characterized by destruction of bone, affecting both primary and secondary teeth, and hyperkeratosis, affecting the palms of the hands and soles of the feet. Germ-line mutation results in a loss of function in cathepsin C. Without cathepsin C, granzymes cannot be activated, and infected and tumor cells cannot be killed.

Question 7

When a CTL with FasL interacts with a target cell possessing Fas, what happens to the target cell?&#10;A) The target cell dies via apoptotic cell death.&#10;B) Nothing; the target cell is healthy and remains intact.&#10;C) The target cell goes into cell cycle arrest and repairs damage.&#10;D) Nothing, but the interaction with the target cell causes death of the CTL.

Accepted Answer

The interaction with FasL on the T cell activates death domains on Fas of the target cell, leading to apoptotic cell death of the target cell, not the CTL. The CTL is not harmed by this interaction. However, if the CTL possessed Fas and the target cell expressed FasL, then the target cell could kill the T cell, and this is the case occasionally with tumor cells that express FasL as a protective mechanism against an immune response.

Question 8

Which of the following is a method that tumors use to evade the immune response?&#10;A) Producing IL-2 analogs&#10;B) Reducing TAP function&#10;C) Upregulating MHC class I molecules&#10;D) Engaging Fas receptors on T cells to cause T cell death

Accepted Answer

Some tumor cells produce Fas ligand (FasL) on the cell surface and are able to engage Fas receptors on T cells (T cells express both Fas and FasL). By engaging Fas on the T cell, the tumor cell is able to cause apoptotic cell death of the T cell because the death domains are activated on Fas.

Question 9

Cytotoxic (CD8+) T cells (CTLs) are activated by:&#10;A) Antigen presented on MHC class I molecules&#10;B) Antigen presented on MHC class II molecules&#10;C) Antigen presented on MHC class I or II molecules&#10;D) CTLs do not require activation to kill

Accepted Answer

CTLs are activated by dendritic cells and target cells expressing antigen on MHC class I molecules.

Question 10

Which of the following cells may contain perforin and granzymes?
I. Tumor cells
II. CD4 T cells
III. CD8 T cells

A) I only
B) III only
C) I and II
D) II and III
E) I, II, and III

Accepted Answer

Both CD4 and CD8 cells, as well as natural killer (NK) cells, may contain perforin and granzymes. CD8 and NK cells always possess perforin and granzymes, but only a few CD4 T cells possess the cytotoxic components.

Deck 20: Cytotoxic T Cells