In a FantasticVoyagePlot, more often than not, the voyagers will have to contend with white blood cells that are instinctively trying to remove them from the bloodstream. (Hey, the white blood cells don't know the voyagers are there to help!) Either the voyagers will meet them head on and attack, or a ChaseScene will ensue. White blood cells usually don't chase pathogens, they just float around and eat any threats that they bump into.

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!!Examples:

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[[folder:Anime & Manga]]
* The orange blobs within the tree in ''Anime/PokemonLucarioAndTheMysteryOfMew'' are described as its equivalent to white blood cells. They specifically home in on any nearby humans.
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[[folder:Fanfiction]]
* VERY squicky example in ''Fanfic/ThousandShinji'': when Iruel makes his appearance and tries to infect Rei, her body is transformed into a [[NauseaFuel bloated, pus-dripping mass of flesh]] that is a literal FACTORY of all kinds of nasty viruses purpose-made to kill Iruel's nanites.
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[[folder:Live Action TV]]
* In the ''Series/DoctorWho'' story "The Invisible Enemy", the Doctor and Leela travel inside the Doctor's body [[note]]Yes, the Doctor travels inside his own body. ItMakesSenseInContext.[[/note]] to deal with an alien infection. At one point, they're attacked by white blood cells, but the Doctor uses a nearby nerve cluster to send them a fake message summoning them to a different part of the body. (This wouldn't work in a human body, where white blood cells just wander aimlessly and deal with whatever they happen to come across, but maybe a Time Lord's immune system works differently.)
* In an episode of the new ''Series/OuterLimits'' series, a spaceship crew punches a hole into another dimension, which they assume to be [[SubspaceOrHyperspace hyperspace or subspace]]. The main character, who is descended from {{Magical Native American}}s, starts to believe that it is actually the bloodstream of the living universe. What they originally thought to be asteroids turn out to have a similar structure to human white blood cells, except they use gravity to kill infection.
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[[folder:Video Games]]
* In ''[[VideoGame/MarioAndLuigiBowsersInsideStory Mario & Luigi: Bowser's Inside Story]]'', one room inside Bowser features a large worm boss that is eating what appear to be white knights. After you defeat the worm, the knights ambush you and send you falling. It's not explicitly stated that these are white blood cells, but Toadbert's description of their intent matches perfectly.
** There's also Alpha Kretin, who is by no means a white blood cell, but attacks in the same way, swarming Princess Peach and then taking some kind of monster form after it's spun away by Mario and Luigi. Sadly, it also appears in the Gauntlet.
* Although it's not a physical example, Censors in ''VideoGame/{{Psychonauts}}'' are a mental equivalent. Censors roam the psyche and censor out anything that doesn't belong, including hallucinations, paranoias... and visiting Psychonauts. In fact, one of the first signs that Boyd's mind [[{{Understatement}} isn't doing so well]] is that ''there are no Censors whatsoever in there.''
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[[folder:Western Animation]]
* ''WesternAnimation/OsmosisJones'' anthropomorphisizes the entire human body, giving all the various cells and such names and allowing them to speak and develop friendships with other cells. The white blood cells are treated like the police, so they get a lot of chase scenes with equally anthropomorphic pathogens.
* During the ''WesternAnimation/TeenTitans'' episode "Crash", Cyborg gets infected with a virus, so Gizmo and Beast Boy go micro and fight the virus. One scene shows white blood cells chasing them.
* During an episode of ''WesternAnimation/TheMagicSchoolBus'', "Inside Ralphie", the classroom piles into their bus and goes micro to figure out what's making Ralphie get sick. They encounter white blood cells, which identify the bus as a pathogen and start a chase scene. The white blood cells are shown "sniffing" for pathogens, even though they don't have noses.
* In the "TV Dinner" episode of ''WesternAnimation/MegasXLR'', Coop and company enter a planet-sized monster's body, where the titular HumongousMecha is bacterial-sized by comparison. They get attacked by the extra-terrestrial equivalent of white blood cells.
* Avoided completely in ''WesternAnimation/{{Futurama}}'' when the Planet Express crew go inside Fry's body with nanomachines and are never attacked by any part of his immune system. Though the sentient parasite worms that got there first and remodeled his body to their liking may have something to do with that. If so, FridgeHorror since they are forced to leave at the end of the episode....
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[[folder: Truth In Television]]
* [[http://www.biochemweb.org/neutrophil.shtml This video]] shows a white blood cell chasing a staphylococcus bacterium.
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