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← Theoretical 2

Q73 — PD-1 Immune Checkpoint Signaling

Theoretical 2 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Immune Physiology

Immune checkpoint molecules regulate the immune system and prevent excessive immune response. The programmed death molecule 1 or PD-1 is expressed on the T cells and is involved in a co-inhibitory pathway that suppresses T cell function. PD-1 has an important role in the immune system development, and allows tolerance to its own proteins. There are two known ligands for PD-1, the PD-L1 and PD-L2, and they are both known to induce the co-inhibitory signaling. Cancer cells take advantage of this signaling pathway to avoid being killed by immune cells. Researchers have found a way to target those molecules and this resulted in reduction of tumor volume, mediated through the immune system.

Determine whether the following statements are true or false.

A. PD-1 dysfunction can lead to development of autoimmune diseases.
B. PD-1, when binding to its ligand-PD-L1, activates antitumor immune response.
C. The inhibition of the PD-1/PD-L1-axis prevents T cells from recognizing tumor cells as "self" and enables their destruction
D. The inhibition of the PD1-PD-L2 axis will lead to recovery from an autoimmune disorder.
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Question reproduced from IBO 2022, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)