InnkaFriz t1_iujchnc wrote on October 31, 2022 at 7:37 PM

Reply to comment by sharplydressedman in How do white blood cells know in which direction there is a bacteria? by Enocli

Thanks for the info! Follow up - is there a “red list” of bacteria patterns? Because afaik we do have a lot of bacteria we basically rely on for our health, and I’d assume that there is some mechanism to ignore them

sharplydressedman t1_iujzkmj wrote on October 31, 2022 at 10:20 PM

Well, yes and no - this will require a bit of a deeper dive into immunology. Our immune system has two general branches, the adaptive (slower but can "learn") and innate (quick but limited to pre-determined common patterns). There isn't a "red list" per se for the innate immune system since it is evolutionarily more efficient for our innate immune cells to have the receptors for the definitely dangerous patterns, and let the adaptive immune system "learn" which patterns are safe.

As a metaphor for the innate immune system, the TSA displays a list of things that are definitely banned on planes. They may not need to have a list of things that are "definitely safe", they can figure that out along the way.

Anyway to return to your question, the adaptive immune system DOES have the ability to identify molecules that are safe. "Mucosal tolerance" refers to the ability of the body to suppress immune responses against antigens that are encountered in the gastrointestinal tract. This is not only to protect the commensal bacteria that live in our intestines, but also prevents our immune system from flaring up against the molecules in our food.

CynicalDarkFox t1_iujieo7 wrote on October 31, 2022 at 8:17 PM

From what I know, that helpful bacteria is more situated in the GI tract rather than floating around the body.

However, it wouldn’t be a long shot to assume that helpful/neutral bacteria wouldn’t give off these chemicals that a pathogen would either since they aren’t exactly there to propagate selfishly.

WasabiSteak t1_iujm7cp wrote on October 31, 2022 at 8:43 PM

Maybe they're not "selfish" in the GI tract, but I don't think they would behave once they get into the bloodstream.

Jimmy_Smith t1_iujz6c0 wrote on October 31, 2022 at 10:17 PM

These are called opportunistic pathogens. They may normal gut bacteria like e. coli, but when it enters the bloodstream or travels up your urethra to your kidneys they will kill you.

Now some of these bacteria may stay put either because they are inhibited by competing bacteria which is why some research focuses on transplating gut microbiome, but sometimes bacteria wait until they have enough around for a massive attack through quorum sensing.

tedivm t1_iuk9uu7 wrote on October 31, 2022 at 11:42 PM

>but sometimes bacteria wait until they have enough around for a massive attack through quorum sensing.

How does that work?