Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff Lauren Bogelbaum. Here,
Speaker 1: you might think of your body sort of like a
Speaker 1: fabulous estate with a lot of different departments and individual
Speaker 1: workers that keep the household running. For this metaphor, whether
Speaker 1: you want to imagine yourself as a medieval castle or
Speaker 1: a countryside manor, or more of a well staffed but
Speaker 1: nonetheless haunted mansion is up to you. You might say
Speaker 1: that you've got a kitchen staff in your digestive system,
Speaker 1: because it prepares nutrients for the whole household to use.
Speaker 1: Organs like your kidneys, are part of the cleaning staff.
Speaker 1: Your body also keeps a sharp security staff on hand
Speaker 1: in the form of your immune system. There are two
Speaker 1: subdepartments or branches within the immune system, the innate and
Speaker 1: the adaptive. A lot of germs that enter your body
Speaker 1: get dealt with with a swiftness by your innate immune system.
Speaker 1: This is a whole organization of defenses that keep out
Speaker 1: and kick out any sort of home invader at the home,
Speaker 1: in this case being you. Your innate immune system includes
Speaker 1: your skin and mucous membranes, which are physical barriers, and
Speaker 1: some cells and enzymes that scan for attack and kill
Speaker 1: any germs that do make it in of like in
Speaker 1: the state's physical walls and its camera network and security guards.
Speaker 1: The innate immune system is fairly automated and can't distinguish
Speaker 1: between different types of invaders that well, but it's really
Speaker 1: effective at stopping them before they make you sick. Unfortunately
Speaker 1: for us, some germs have evolved to evade our innate
Speaker 1: immune system. When for whatever reason, a germ survives in
Speaker 1: your body and keeps multiplying, the security guards of the
Speaker 1: innate immune system call into action that second branch, your
Speaker 1: adaptive immune system. It's called adaptive because it can learn
Speaker 1: about different germs and respond specific to each. It functions
Speaker 1: sort of like a network of live in detectives or
Speaker 1: special agents that build a database of all the germs
Speaker 1: they fought off over the course of your life. This
Speaker 1: is super cool because I mean, A, it keeps us alive,
Speaker 1: but B it also prevents us from getting sick from
Speaker 1: certain diseases twice like chicken pox. Once you've had it,
Speaker 1: you'll probably never get it again. The adaptive immune system
Speaker 1: is also why vaccines work. We can introduce a harmless
Speaker 1: version of a germ or bits of a germ to
Speaker 1: our adaptive immune system, and it'll learn how to recognize
Speaker 1: that germ, so should the real thing try to invade
Speaker 1: at a later time and date, your body can spring
Speaker 1: into action and fight it off quick You can see
Speaker 1: our whole episode on vaccines for more about that. The
Speaker 1: immune system and its two branches are hugely complex and interrelated.
Speaker 1: When it's all working correctly, it sets up a lot
Speaker 1: of checks and balances so that the cells, the workers
Speaker 1: within the system are aggressive about fighting off invaders, but
Speaker 1: also don't make mistakes in the form of friendly fire
Speaker 1: or too much collateral damage. But because of that complexity,
Speaker 1: there's also a lot of things that can go wrong. Today,
Speaker 1: let's talk more about how your adaptive immune system works
Speaker 1: and what can happen when it turns against you. The
Speaker 1: primary workers in your adaptive immune system, your detectives or
Speaker 1: special agents, are a category of cells called lymphocytes. They're
Speaker 1: called that because when they're not actively fighting off an infection,
Speaker 1: they mostly hang out dormant in your lymph nodes. These
Speaker 1: are small organs that you have many of throughout your body,
Speaker 1: though you might be most familiar with the two in
Speaker 1: your upper neck on either side of your windpipe. You
Speaker 1: might have had a doctor or parent feel for those
Speaker 1: when you've had a cold, because during an infection, they're
Speaker 1: a base of operations for lymphocytes, so if you're fighting
Speaker 1: something off, they tend to swell up. There are two
Speaker 1: categories of lymphocytes, B cells and T cells. T cells
Speaker 1: are called that because they mature in the thymus after
Speaker 1: having been created in your bone marrow. B cells are
Speaker 1: created and mature in the bone marrow, which is why
Speaker 1: they're called B cells. That's not super important, but I
Speaker 1: just learned that, and I had always wondered about the names,
Speaker 1: so I thought i'd share. Anyway, In their downtime, your
Speaker 1: lymphocytes are mostly hanging out in their headquarters, your lymph nodes,
Speaker 1: waiting for a call to action. When your innate immune
Speaker 1: system encounters germs, specialized security guard cells come to lymph
Speaker 1: nodes to tell the lymphocytes about it. What's technically happening
Speaker 1: is that the innate immune cell eats the germ and
Speaker 1: breaks it apart and displays bits of the germ on
Speaker 1: its surface. But that gets real grizzly for our metaphor,
Speaker 1: So let's say it's like showing some security cam footage.
Speaker 1: These germ bits or identic buying footage are what's called antigens.
Speaker 1: We've talked about antigens on the show before. There are
Speaker 1: molecules that occur on the surface of germs and cells
Speaker 1: and other stuff that your immune system can use to
Speaker 1: id whatever it is. If the thing in question is
Speaker 1: from your own body and thus belongs there, your immune
Speaker 1: system should recognize that. If it's not, your adaptive immune
Speaker 1: system's job is to create a specific attack against germs
Speaker 1: bearing that antigen and then remember it later. Here's how
Speaker 1: it works. The T cells in your lymph nodes can
Speaker 1: test a presented antigen and see whether they recognize it
Speaker 1: because your body has fought a germ with it before.
Speaker 1: Each individual T cell tests for, or recognizes, or fits
Speaker 1: to a single antigen like a key in a lock.
Speaker 1: Even if it's a new to you antigen, that's okay.
Speaker 1: Eventually your system will find a T cell that fits
Speaker 1: well enough as a remembered antigen. That's great. The whole process
Speaker 1: can go quicker. When a T cell fits to an antigen,
Speaker 1: it activates a response like a red alert. The T
Speaker 1: cells starts to replicate rapidly, producing copies of itself that
Speaker 1: are all custom fitted to that particular antigen. This is
Speaker 1: really helpful because T cells are sort of like your
Speaker 1: body's targeted assassins. They seek out and attack germs and
Speaker 1: infected cells directly based on the particular antigen that they recognize.
Speaker 1: T cells can also chemically signal other immune cells to
Speaker 1: come help and can help activate your B cells. B
Speaker 1: cells are sort of like your weapons experts. They create
Speaker 1: what's called antibodies. Antibodies are specific proteins that your body
Speaker 1: builds to match specific antigens. Antibodies can bind to their
Speaker 1: matching antigen on the surface of a germ, rendering the
Speaker 1: germ unable to do any harm, and also serve to
Speaker 1: flag that germ or a germ infected cell for destruction.
Speaker 1: At this point in the estate metaphor, I'm not sure
Speaker 1: exactly what kind of household we're running here, maybe a
Speaker 1: supervillain's compound, but let's just roll with it. So, after
Speaker 1: your immune system has cleared an infection, it will stockpile
Speaker 1: that particular antibody and keep around some T cells that
Speaker 1: recognize that antigen in most cases forever. So if your
Speaker 1: immune system encounters antigens of the same type later on
Speaker 1: Bada bing Bada boom, where Bada bing boda boom indicates
Speaker 1: that networks within networks of intracellular communication and coordinated efforts
Speaker 1: will occur. It's all again really complex, which means a
Speaker 1: lot of different things can go wrong. For example, not
Speaker 1: everything that your immune system IDs using antigens as not
Speaker 1: self and thus potentially unsafe, is actually a threat. This
Speaker 1: is how we wind up with allergies to not just
Speaker 1: harmless but actively adorable things like cats and flowers. For
Speaker 1: some reason, your immune system looks at a granule of
Speaker 1: pollen or pet dander and tries to clear it out
Speaker 1: of your body with the same kind of extreme prejudice
Speaker 1: it would a disease causing germ. Your innate immune system
Speaker 1: triggers lots of inflammation to help get fighting resources to
Speaker 1: the area, say your nose, but there's really nothing to fight,
Speaker 1: so you just wind up swollen and itchy. There are
Speaker 1: also some types of germs that actively mess with your
Speaker 1: immune system. That's what originally made the human immuno deficiency
Speaker 1: viruses or HIV so scary. HIV infects and kills immune
Speaker 1: system cells like T cells in order to spread. There
Speaker 1: have been some amazing advances in treating and preventing HIV
Speaker 1: in recent years. It's very manageable. Now I'll have to
Speaker 1: do a whole episode about it. Anyway. There are also
Speaker 1: a number of conditions that happen when the adaptive immune
Speaker 1: system starts confusing your own cells for invaders. Every cell
Speaker 1: in our bodies should be coded as self thanks to
Speaker 1: antigens on the cell's surface. It's sort of like wearing
Speaker 1: an id. Bad antigens tell your immune system at a glance,
Speaker 1: hey I'm cool, I work here. There are entire processes
Speaker 1: in your body to curate your T cells and B cells,
Speaker 1: but keep their activity in check and make sure that
Speaker 1: ones that seem to want to attack self codd cells
Speaker 1: don't get into circulation in the first place. But it
Speaker 1: still happens, and this category of conditions is called autoimmune disorders.
Speaker 1: It includes things like arthritis, in which your immune system
Speaker 1: attacks your joints, type one diabetes in which it attacks
Speaker 1: your pancreas, multiple sclerosis which damages nerve cells, and psoriasis,
Speaker 1: which damages the skin leading to scaly, pass or other problems.
Speaker 1: Autoimmune disorders tend to be frustrating to treat, after all,
Speaker 1: You can't just remove and replace a malfunctioning immune system
Speaker 1: the way you might a kidney. Also, we don't understand
Speaker 1: exactly why any given autoimmune disorder happens. There is a
Speaker 1: lot of research going into this, and we've got a
Speaker 1: lot of good starting concepts, but again, the entire immune
Speaker 1: process is so complex that it's hard to nail things down.
Speaker 1: For example, researchers have identified sets of genes that code
Speaker 1: for things like how your immune cells recognize antigens or
Speaker 1: how your body's cells produce their self ID. It makes
Speaker 1: sense that errors in this coding could lead to problems.
Speaker 1: Other research has looked into malfunctions in T cells that
Speaker 1: lead them to overproduce those signal molecules that call in
Speaker 1: the troops, which also leads to inflammation, which tends to
Speaker 1: be an issue in autoimmune disorders. Yet other research is
Speaker 1: diving in two malfunctions in a subset of T cells
Speaker 1: called regulatory T cells, that are supposed to regulate their
Speaker 1: fellow workers in the immune system, shutting down the red
Speaker 1: alert after an infection has been cleared, and suppressing excess activity.
Speaker 1: Even when we do have a decent idea of what's
Speaker 1: going wrong, immune disorders of all types can be difficult
Speaker 1: to treat, but there are increasingly effective therapies that can
Speaker 1: ease symptoms or even target particular immune system activities to
Speaker 1: help bring it back closer to normal. As always, if
Speaker 1: you or a loved one is experiencing strange inflammation or
Speaker 1: other irritating or painful symptoms with no obvious cause. You
Speaker 1: know you didn't stub your skin, definitely get in touch
Speaker 1: with a healthcare professional. They'll be able to help you
Speaker 1: get a diagnosis and a treatment plan, even if your
Speaker 1: body is a supervillain's layer that may or may not
Speaker 1: be haunted. Today's episode is an original written by me.
Speaker 1: Brain Stuff is production of iHeart Radio and is produced
Speaker 1: by Tyler Klang. Four more podcasts from iHeartRadio visit the
Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your
Speaker 1: favorite shows.