Today’s biology lesson answers the question Why Do We Keep Getting Diseases from Bats? with a look at the differences between our respective immune systems.

…bat cells just continually assume they’re under attack and never stop fighting viruses, regardless of whether they’ve detected any. This is surprising. Interferon is a really powerful molecule, and continually producing it should have the same effect on a cell as continually putting a factory on red alert. It should make the cell run much worse, and cause a lot of collateral damage.

After all, when this sort of immune system overreaction happens in humans, humans get serious disorders, like Multiple Sclerosis and Lupus. Bats do not tend to get these. In fact, many bat species live around 20 years on average, which is not only way longer than it should have with its overactive immune system, but is exceptionally long for such a small animal. To give a comparison, rats live a year or two, as do rabbits.

There’s lots more, explaining how bats can live such relatively long lives with an “always-on” immune system, and also why their immune system evolved to be that way.

As an aside, I wasn’t aware that we had Natural Killer (NK) cells…

NK cells are as heavy duty as their name implies; while their cousins, T cells, kill any cell that displays signs of being infected, NK cells kill any cells that don’t display signs of being not infected. Viruses will frequently prevent cells from indicating that they’re infected, so NK cells just kill any cell that looks like it’s hiding something.

No messing around there!