Immunity system complexity: attack killer cells have memory (Introduction)

by David Turell @, Monday, May 13, 2019, 18:20 (12 days ago) @ David Turell

These are not the immune attack cells, and this discovery is a surprise:

"Scientists have long believed that humans and many other mammals have two types of immune systems: innate and adaptive. The former is driven by natural killer (NK) cells, which attack any cell it identifies as non-self, the latter by B and T cells that form long-term memories of particular antigens they meet so they are more prepared to fight that antigen in the future.

"The NK cells are thought to form the first barrier of defense against any incoming pathogen, poking holes in the cells to kill them. Several years ago, researchers discovered that these NK cells may be able to form “memories” of previous antigen exposures and play a role in adaptive immunity, independent of B and T cells—in mice, at least.


"These results support what her group had found previously, that NK cells can recall past encounters with pathogens.

"But there was one surprise. Only the NK cells harvested from the animals’ livers seemed to “remember” the HIV envelope, not the ones from their spleens. Both groups of NK cells that came from the spleens—those that had been exposed to the vaccination and those that hadn’t—reacted as if they’d never been exposed to the HIV envelope virus.

The second part of the study used actual humans, rather than humanized mice. Paust and her team recruited adults aged 40–60 who had had chicken pox when they were children and injected them with glycoproteins from the chicken pox virus. “It’s similar to a TB test,” she explains, in that people who have had chicken pox will develop a blister-like response on the skin at the site of injection.

"Once the blister formed, scientists collected some of the fluid and isolated NK cells that had been recruited to the site. Unlike NK cells found elsewhere in the body, these cells were active and fighting the antigens, implying that the adaptive memory of these cells had lasted decades.

"Paust says she believes the cells were likely to have originated in the liver, based on comparisons to liver-derived cells. “This is as close as we could get in humans,” she says, admitting that this is not a perfect test, but that she hopes clinicians who have access to liver and spleen tissue after surgeries might have the opportunity (with their patient’s consent) to explore further.

"Understanding how NK cells form adaptive memories may help researchers develop more-effective vaccines that stimulate immunity from all three types of capable immune cells. Plus, if scientists can identify biomarkers showing when NK cells are responding to familiar infections, it may provide clues as to why some vaccines are more effective than others. "

Comment: Life had to be developed with an immune system present from the beginning, since it had to recognized viruses were also present after arriving early on in the development of biologic forms. Immunity systems must always have an evolving stored memory of past infections. Too complex for chance development. Designed.

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