The Spoils of War — How T Cells Refuel to Wage War on Pathogens

A killer T cell attacks an infected cell.

In humans, T cells fight viruses and other invaders. Scientists have long thought T cells simply killed an enemy and then moved on to fight others, but new research suggests that some T cells use the spoils of their battles to win the larger war.

White blood cells are part of the immune system, the human body’s main defense against viruses and other infectious agents, all of which are called pathogens. Pathogens take over the machinery of a cell and cause it to manufacture more pathogens, leading to infection. The body has six major classes of white blood cells, each offering specific weaponry and tactics for combating infection. One class of white blood cells is the lymphocytes, which include T cells and B cells.

Killer T Cells

One type of T cell, the CD8+ T cell, is known more commonly as a “killer” T cell. It attacks infected cells with cytoxins, which cause the plasma membrane of an infected cell to open, allowing water, ions, and toxins to rush in. The infected cell then swells and bursts, destroying the pathogens that have taken over the cell. Until recently, scientists thought that T cells left their victims after killing them and simply moved on to attack other infected cells. Results of recent research, however, show that the interaction between killer T cells and infected cells is more like that of predator and prey.

Caught “Green-Handed”

Mark Slifka and Carol Beadling, researchers at Oregon Health & Science University’s Vaccine and Gene Therapy Institute, happened upon this discovery while observing interactions between killer T cells and cells infected by a virus.

Slifka and Beadling dyed infected cells with a fluorescent green dye so that these cells could be more easily seen under a microscope. They then unleashed killer T cells that were specific to the virus of the infected cells, to observe their interactions. They watched the small T cells attack and kill the large green infected cells as expected. But Slifka and Beadling noticed something strange. The T cells, which had not been dyed, were themselves turning green as the infected cells broke apart. Slifka and Beadling realized that the T cells were actually eating portions of the infected cells’ membranes. Like a child whose tongue is stained purple from a popsicle, the fluorescent dye was a telltale sign that the killer T cells weren’t just killing the infected cells, they were feeding on them. They had been caught “green-handed.”

A Well-Fed Army

A fluorescent infected cell is killed and partially devoured by killer T cells. (Credit: David Parker and Scott Wetzel/OHSU)

“This is truly a case of microscopic cannibalism,” Slifka says. “And this is the first time we’ve seen virus-specific killer T-cells ingest parts of infected cells.” Slifka thinks that the benefit of this behavior is that T cells can refuel themselves before fighting other infected cells. He compares this to an army of warriors that invades a city, destroys it, but takes care to gather resources that could help it maintain strength in its ongoing war. “Not only do you have this warrior cell coming in and attacking these virus factories, but it’s able to take away nourishment from this in order to help it to continue the fight against the infection,” he says.

A similar response to virus-infected cells by CD4+ T cells, also known as “helper” T cells, was observed by researcher David Parker, also of the Oregon Health & Science University. The value, Slifka says, of these discoveries about T cells is that the same experimental techniques used to study interactions with pathogens could be applied to observe and measure the response of T cells to a vaccine.

Hope for Vaccines?

A vaccine is a substance that carries the identifying markers, or antigens, of a virus but does not have the destructive capabilities of the actual virus. Some vaccines are made from dead viruses. Others are weakened versions of a virus. A vaccine triggers an immune response. The body produces lymphocytes such as B and T cells that will be able to recognize the real virus should it ever appear in the body. In other words, a vaccine teaches the human body how to identify and defeat a virus, but without putting the body through the danger of the real viral infection.

Slifka’s findings suggest that if a vaccine were marked with a fluorescent green dye, and killer T cells were then unleashed to attack and consume the vaccine, scientists could accurately measure the interaction between the vaccine and the killer T cells. This could help determine a vaccine’s effectiveness, as well as the dosage needed to immunize a person.

More to Explore

Check out the following sites to hear from Dr. Slifka, read more about his discovery, and watch killer T cells as they kill and eat an infected cell.

Comments

  1. wow….thats interesting. i didnt know that.

  2. wow i learned a lot from this.

  3. The Spoils of War How T Cells Refuel to Wage War on Pathogens is really interesting because it talks about the cells and all stuff it does and i learned that the white blood cells are the lymphocytes, but the article is really interesting and it has a lot of things that i didn’t know what they meant or what they were but now i know more stuff that i learned and i think that is really good and it has a lot of informations

  4. Taylor (MVHS) says

    I thought this was a cool article. It is the beginning of finding more vaccines, also i found it funny that the T cells actually eat the virus and use its resources for another “attack.” These T cells are very smart!!!!!

  5. Toby [MVHS] says

    same with the other person this article was very cool. and i found it even better that that we have like little t-cell zombies in us. haha. zombies…what if the t-cells started to attack us.
    scary stuff man.

  6. Shayna Ridley (MVHS) says

    This article was very interesting to read. Science has many cool facts to it. It made me realize how complex our body really is. I cant beleive that the T cells would actually eat the virus. Pretty insane but definitely smart!

  7. Joseph [mmhs] says

    This article toke me a long time to look over for me to get it. then as I read on i understood about it. What i think about it I think that it isnt that Interesting I thought it was very boring and I dont see the big deal about it.

  8. Weston (MMHS) says

    I think its interesting to read about this how the T cells would eat the virus but then couldn’t the T cells get infected them self? With Vaccines couldn’t you also catch the virus if your body is very weak against that virus?

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