In these videos, the killer T cells are dyed white, the helper T cells are dyed green, and the dendritic cells are dyed red. According to the project’s researcher Scott Mueller, it’s the “first time that we can see all of these immune cells at once responding to an infection.”
The cells were dyed and examined in live tissue under a (very) powerful microscope. The cells themselves are tiny — about one quarter the width of a human hair — and the images needed to be magnified over 400 times.
The upshot is that this kind of information can help doctors come up with better vaccines. They believe the way the cells work together should be the same for other viruses, such as HIV.