Checkpoint Blockade: Taking a Brake Off a T Cell · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Releasing T cells to fight tumours

Science · The Human Body · ages 22-24
Name ______________________   Date ____________

  1. Where does CTLA-4 act in a T cell response?

    • Early, during priming, by outcompeting CD28
    • Late, by quieting cells already inside the tissue
    • Outside the body, before any antigen appears

  2. Which T cells kill abnormal cells directly?

    • Regulatory T cells that calm the response
    • Helper T cells carrying CD4
    • Cytotoxic T cells carrying CD8

  3. A naive T cell switches on whenever it meets any single signal.

    Circle one:   True   False

  4. A tumour hid its presentation machinery. What happens when brakes lift?

    • It stays invisible and gains little
    • It responds better than any other type
    • It switches to antibody production instead

  5. A tumour has many mutations and intact presentation. What do you predict for blockade?

    • A poor response because foreignness never matters
    • A strong response, as the tumour looks foreign
    • No response unless the burden drops first

  6. A patient develops inflamed gut during blockade. How do you interpret it?

    • Off target poisoning unrelated to the mechanism
    • An on target effect of released T cells striking healthy tissue
    • Proof the drug never reached the tumour

  7. A colleague calls these drugs T cell creators. What do you correct?

    • They free existing held back cells through the cell mediated arm
    • They work through antibodies against outside targets
    • They erase all immune memory for safety

  8. PD-1 blockade fails although dosing was perfect. Presentation is absent. What is the flaw in repeating the dose?

    • The dose was too low to matter
    • No displayed antigen means freed cells stay blind, so more drug cannot help
    • PD-1 acts during early priming instead
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Releasing T cells to fight tumours W1-mt_f9P4LlaBGb-s1

  1. Early, during priming, by outcompeting CD28 · CTLA-4 raises the threshold for activation at the priming step.
  2. Cytotoxic T cells carrying CD8 · CD8 killers destroy infected or abnormal cells directly.
  3. False · It needs its antigen on MHC plus a second costimulatory push.
  4. It stays invisible and gains little · Without displayed fragments, freed cells still cannot see their target.
  5. A strong response, as the tumour looks foreign · Many odd fragments make the tumour look foreign to released cells.
  6. An on target effect of released T cells striking healthy tissue · The same release that fights cancer also hits gut, skin, or glands.
  7. They free existing held back cells through the cell mediated arm · Checkpoint drugs release what was held back, which explains who benefits.
  8. No displayed antigen means freed cells stay blind, so more drug cannot help · You must fix visibility first, since the cells freed already sit at the fight.
Worksheet · LightMySky