When did Horizon Season 11 Episode 1 air?
Horizon Season 11 Episode 1 aired on January 7, 1974.


Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before.
This episode of Horizon explains how our body fights infections and cancers and brings us up-to-date on recent research in immunology.
Direct answers for episode-level questions and details.
Horizon Season 11 Episode 1 aired on January 7, 1974.
This episode runs for approximately 60 minutes.
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