1 00:00:01,840 --> 00:00:08,639 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff Lauren Bogelbaum. Here, 2 00:00:10,480 --> 00:00:12,840 Speaker 1: you might think of your body sort of like a 3 00:00:12,880 --> 00:00:16,759 Speaker 1: fabulous estate with a lot of different departments and individual 4 00:00:16,800 --> 00:00:20,920 Speaker 1: workers that keep the household running. For this metaphor, whether 5 00:00:21,000 --> 00:00:24,040 Speaker 1: you want to imagine yourself as a medieval castle or 6 00:00:24,079 --> 00:00:27,720 Speaker 1: a countryside manor, or more of a well staffed but 7 00:00:27,760 --> 00:00:32,120 Speaker 1: nonetheless haunted mansion is up to you. You might say 8 00:00:32,159 --> 00:00:34,880 Speaker 1: that you've got a kitchen staff in your digestive system, 9 00:00:34,920 --> 00:00:37,960 Speaker 1: because it prepares nutrients for the whole household to use. 10 00:00:38,720 --> 00:00:41,320 Speaker 1: Organs like your kidneys, are part of the cleaning staff. 11 00:00:42,479 --> 00:00:45,680 Speaker 1: Your body also keeps a sharp security staff on hand 12 00:00:45,760 --> 00:00:48,760 Speaker 1: in the form of your immune system. There are two 13 00:00:48,800 --> 00:00:52,800 Speaker 1: subdepartments or branches within the immune system, the innate and 14 00:00:52,960 --> 00:00:56,440 Speaker 1: the adaptive. A lot of germs that enter your body 15 00:00:56,480 --> 00:01:00,440 Speaker 1: get dealt with with a swiftness by your innate immune system. 16 00:01:01,000 --> 00:01:04,160 Speaker 1: This is a whole organization of defenses that keep out 17 00:01:04,200 --> 00:01:07,040 Speaker 1: and kick out any sort of home invader at the home, 18 00:01:07,080 --> 00:01:11,080 Speaker 1: in this case being you. Your innate immune system includes 19 00:01:11,080 --> 00:01:14,640 Speaker 1: your skin and mucous membranes, which are physical barriers, and 20 00:01:14,760 --> 00:01:18,600 Speaker 1: some cells and enzymes that scan for attack and kill 21 00:01:18,680 --> 00:01:21,280 Speaker 1: any germs that do make it in of like in 22 00:01:21,319 --> 00:01:25,200 Speaker 1: the state's physical walls and its camera network and security guards. 23 00:01:26,319 --> 00:01:29,919 Speaker 1: The innate immune system is fairly automated and can't distinguish 24 00:01:29,959 --> 00:01:33,240 Speaker 1: between different types of invaders that well, but it's really 25 00:01:33,280 --> 00:01:37,720 Speaker 1: effective at stopping them before they make you sick. Unfortunately 26 00:01:37,760 --> 00:01:40,839 Speaker 1: for us, some germs have evolved to evade our innate 27 00:01:40,880 --> 00:01:44,920 Speaker 1: immune system. When for whatever reason, a germ survives in 28 00:01:44,959 --> 00:01:48,520 Speaker 1: your body and keeps multiplying, the security guards of the 29 00:01:48,520 --> 00:01:52,400 Speaker 1: innate immune system call into action that second branch, your 30 00:01:52,520 --> 00:01:57,400 Speaker 1: adaptive immune system. It's called adaptive because it can learn 31 00:01:57,480 --> 00:02:02,800 Speaker 1: about different germs and respond specific to each. It functions 32 00:02:02,920 --> 00:02:05,640 Speaker 1: sort of like a network of live in detectives or 33 00:02:05,680 --> 00:02:08,680 Speaker 1: special agents that build a database of all the germs 34 00:02:08,720 --> 00:02:12,160 Speaker 1: they fought off over the course of your life. This 35 00:02:12,360 --> 00:02:15,480 Speaker 1: is super cool because I mean, A, it keeps us alive, 36 00:02:15,760 --> 00:02:18,480 Speaker 1: but B it also prevents us from getting sick from 37 00:02:18,520 --> 00:02:22,440 Speaker 1: certain diseases twice like chicken pox. Once you've had it, 38 00:02:22,480 --> 00:02:26,359 Speaker 1: you'll probably never get it again. The adaptive immune system 39 00:02:26,480 --> 00:02:29,919 Speaker 1: is also why vaccines work. We can introduce a harmless 40 00:02:30,000 --> 00:02:32,200 Speaker 1: version of a germ or bits of a germ to 41 00:02:32,320 --> 00:02:35,080 Speaker 1: our adaptive immune system, and it'll learn how to recognize 42 00:02:35,080 --> 00:02:38,040 Speaker 1: that germ, so should the real thing try to invade 43 00:02:38,080 --> 00:02:40,600 Speaker 1: at a later time and date, your body can spring 44 00:02:40,639 --> 00:02:43,720 Speaker 1: into action and fight it off quick You can see 45 00:02:43,760 --> 00:02:47,360 Speaker 1: our whole episode on vaccines for more about that. The 46 00:02:47,360 --> 00:02:51,800 Speaker 1: immune system and its two branches are hugely complex and interrelated. 47 00:02:52,360 --> 00:02:54,760 Speaker 1: When it's all working correctly, it sets up a lot 48 00:02:54,760 --> 00:02:58,040 Speaker 1: of checks and balances so that the cells, the workers 49 00:02:58,080 --> 00:03:01,680 Speaker 1: within the system are aggressive about fighting off invaders, but 50 00:03:01,880 --> 00:03:05,040 Speaker 1: also don't make mistakes in the form of friendly fire 51 00:03:05,320 --> 00:03:10,280 Speaker 1: or too much collateral damage. But because of that complexity, 52 00:03:10,440 --> 00:03:14,520 Speaker 1: there's also a lot of things that can go wrong. Today, 53 00:03:14,680 --> 00:03:17,400 Speaker 1: let's talk more about how your adaptive immune system works 54 00:03:17,520 --> 00:03:21,880 Speaker 1: and what can happen when it turns against you. The 55 00:03:22,040 --> 00:03:25,680 Speaker 1: primary workers in your adaptive immune system, your detectives or 56 00:03:25,720 --> 00:03:30,880 Speaker 1: special agents, are a category of cells called lymphocytes. They're 57 00:03:30,919 --> 00:03:33,920 Speaker 1: called that because when they're not actively fighting off an infection, 58 00:03:34,200 --> 00:03:38,680 Speaker 1: they mostly hang out dormant in your lymph nodes. These 59 00:03:38,680 --> 00:03:41,440 Speaker 1: are small organs that you have many of throughout your body, 60 00:03:41,800 --> 00:03:44,000 Speaker 1: though you might be most familiar with the two in 61 00:03:44,040 --> 00:03:47,720 Speaker 1: your upper neck on either side of your windpipe. You 62 00:03:47,840 --> 00:03:50,280 Speaker 1: might have had a doctor or parent feel for those 63 00:03:50,320 --> 00:03:53,800 Speaker 1: when you've had a cold, because during an infection, they're 64 00:03:53,840 --> 00:03:57,240 Speaker 1: a base of operations for lymphocytes, so if you're fighting 65 00:03:57,280 --> 00:04:00,920 Speaker 1: something off, they tend to swell up. There are two 66 00:04:01,040 --> 00:04:05,840 Speaker 1: categories of lymphocytes, B cells and T cells. T cells 67 00:04:05,840 --> 00:04:08,520 Speaker 1: are called that because they mature in the thymus after 68 00:04:08,560 --> 00:04:11,600 Speaker 1: having been created in your bone marrow. B cells are 69 00:04:11,640 --> 00:04:14,360 Speaker 1: created and mature in the bone marrow, which is why 70 00:04:14,360 --> 00:04:17,839 Speaker 1: they're called B cells. That's not super important, but I 71 00:04:18,000 --> 00:04:20,480 Speaker 1: just learned that, and I had always wondered about the names, 72 00:04:20,520 --> 00:04:24,840 Speaker 1: so I thought i'd share. Anyway, In their downtime, your 73 00:04:24,920 --> 00:04:29,360 Speaker 1: lymphocytes are mostly hanging out in their headquarters, your lymph nodes, 74 00:04:29,600 --> 00:04:33,920 Speaker 1: waiting for a call to action. When your innate immune 75 00:04:33,960 --> 00:04:39,040 Speaker 1: system encounters germs, specialized security guard cells come to lymph 76 00:04:39,080 --> 00:04:43,920 Speaker 1: nodes to tell the lymphocytes about it. What's technically happening 77 00:04:44,000 --> 00:04:46,720 Speaker 1: is that the innate immune cell eats the germ and 78 00:04:46,800 --> 00:04:49,240 Speaker 1: breaks it apart and displays bits of the germ on 79 00:04:49,320 --> 00:04:53,039 Speaker 1: its surface. But that gets real grizzly for our metaphor, 80 00:04:53,320 --> 00:04:56,520 Speaker 1: So let's say it's like showing some security cam footage. 81 00:04:57,960 --> 00:05:02,720 Speaker 1: These germ bits or identic buying footage are what's called antigens. 82 00:05:03,760 --> 00:05:06,640 Speaker 1: We've talked about antigens on the show before. There are 83 00:05:06,640 --> 00:05:10,440 Speaker 1: molecules that occur on the surface of germs and cells 84 00:05:10,560 --> 00:05:13,680 Speaker 1: and other stuff that your immune system can use to 85 00:05:13,880 --> 00:05:18,240 Speaker 1: id whatever it is. If the thing in question is 86 00:05:18,279 --> 00:05:21,520 Speaker 1: from your own body and thus belongs there, your immune 87 00:05:21,520 --> 00:05:25,719 Speaker 1: system should recognize that. If it's not, your adaptive immune 88 00:05:25,720 --> 00:05:29,719 Speaker 1: system's job is to create a specific attack against germs 89 00:05:29,839 --> 00:05:34,560 Speaker 1: bearing that antigen and then remember it later. Here's how 90 00:05:34,600 --> 00:05:37,640 Speaker 1: it works. The T cells in your lymph nodes can 91 00:05:37,880 --> 00:05:41,599 Speaker 1: test a presented antigen and see whether they recognize it 92 00:05:41,640 --> 00:05:43,600 Speaker 1: because your body has fought a germ with it before. 93 00:05:44,839 --> 00:05:49,160 Speaker 1: Each individual T cell tests for, or recognizes, or fits 94 00:05:49,200 --> 00:05:52,320 Speaker 1: to a single antigen like a key in a lock. 95 00:05:53,520 --> 00:05:55,960 Speaker 1: Even if it's a new to you antigen, that's okay. 96 00:05:56,200 --> 00:05:58,440 Speaker 1: Eventually your system will find a T cell that fits 97 00:05:58,480 --> 00:06:02,640 Speaker 1: well enough as a remembered antigen. That's great. The whole process 98 00:06:02,680 --> 00:06:06,400 Speaker 1: can go quicker. When a T cell fits to an antigen, 99 00:06:06,680 --> 00:06:10,039 Speaker 1: it activates a response like a red alert. The T 100 00:06:10,200 --> 00:06:13,760 Speaker 1: cells starts to replicate rapidly, producing copies of itself that 101 00:06:13,800 --> 00:06:18,120 Speaker 1: are all custom fitted to that particular antigen. This is 102 00:06:18,200 --> 00:06:21,000 Speaker 1: really helpful because T cells are sort of like your 103 00:06:21,000 --> 00:06:25,520 Speaker 1: body's targeted assassins. They seek out and attack germs and 104 00:06:25,640 --> 00:06:30,240 Speaker 1: infected cells directly based on the particular antigen that they recognize. 105 00:06:31,480 --> 00:06:35,000 Speaker 1: T cells can also chemically signal other immune cells to 106 00:06:35,200 --> 00:06:39,840 Speaker 1: come help and can help activate your B cells. B 107 00:06:39,960 --> 00:06:43,839 Speaker 1: cells are sort of like your weapons experts. They create 108 00:06:43,880 --> 00:06:49,160 Speaker 1: what's called antibodies. Antibodies are specific proteins that your body 109 00:06:49,200 --> 00:06:54,159 Speaker 1: builds to match specific antigens. Antibodies can bind to their 110 00:06:54,200 --> 00:06:57,200 Speaker 1: matching antigen on the surface of a germ, rendering the 111 00:06:57,240 --> 00:07:00,640 Speaker 1: germ unable to do any harm, and also serve to 112 00:07:00,800 --> 00:07:04,480 Speaker 1: flag that germ or a germ infected cell for destruction. 113 00:07:05,880 --> 00:07:09,039 Speaker 1: At this point in the estate metaphor, I'm not sure 114 00:07:09,080 --> 00:07:12,160 Speaker 1: exactly what kind of household we're running here, maybe a 115 00:07:12,280 --> 00:07:17,760 Speaker 1: supervillain's compound, but let's just roll with it. So, after 116 00:07:17,800 --> 00:07:21,400 Speaker 1: your immune system has cleared an infection, it will stockpile 117 00:07:21,560 --> 00:07:24,840 Speaker 1: that particular antibody and keep around some T cells that 118 00:07:24,920 --> 00:07:30,960 Speaker 1: recognize that antigen in most cases forever. So if your 119 00:07:30,960 --> 00:07:33,920 Speaker 1: immune system encounters antigens of the same type later on 120 00:07:34,440 --> 00:07:38,520 Speaker 1: Bada bing Bada boom, where Bada bing boda boom indicates 121 00:07:38,560 --> 00:07:43,000 Speaker 1: that networks within networks of intracellular communication and coordinated efforts 122 00:07:43,080 --> 00:07:48,920 Speaker 1: will occur. It's all again really complex, which means a 123 00:07:48,960 --> 00:07:53,640 Speaker 1: lot of different things can go wrong. For example, not 124 00:07:53,920 --> 00:07:57,320 Speaker 1: everything that your immune system IDs using antigens as not 125 00:07:57,520 --> 00:08:02,440 Speaker 1: self and thus potentially unsafe, is actually a threat. This 126 00:08:02,480 --> 00:08:05,120 Speaker 1: is how we wind up with allergies to not just 127 00:08:05,240 --> 00:08:10,560 Speaker 1: harmless but actively adorable things like cats and flowers. For 128 00:08:10,640 --> 00:08:13,480 Speaker 1: some reason, your immune system looks at a granule of 129 00:08:13,520 --> 00:08:16,520 Speaker 1: pollen or pet dander and tries to clear it out 130 00:08:16,560 --> 00:08:19,240 Speaker 1: of your body with the same kind of extreme prejudice 131 00:08:19,240 --> 00:08:23,040 Speaker 1: it would a disease causing germ. Your innate immune system 132 00:08:23,040 --> 00:08:26,200 Speaker 1: triggers lots of inflammation to help get fighting resources to 133 00:08:26,240 --> 00:08:29,960 Speaker 1: the area, say your nose, but there's really nothing to fight, 134 00:08:30,360 --> 00:08:34,840 Speaker 1: so you just wind up swollen and itchy. There are 135 00:08:34,880 --> 00:08:37,960 Speaker 1: also some types of germs that actively mess with your 136 00:08:38,000 --> 00:08:42,840 Speaker 1: immune system. That's what originally made the human immuno deficiency 137 00:08:42,920 --> 00:08:48,000 Speaker 1: viruses or HIV so scary. HIV infects and kills immune 138 00:08:48,000 --> 00:08:52,240 Speaker 1: system cells like T cells in order to spread. There 139 00:08:52,280 --> 00:08:55,280 Speaker 1: have been some amazing advances in treating and preventing HIV 140 00:08:55,360 --> 00:08:58,040 Speaker 1: in recent years. It's very manageable. Now I'll have to 141 00:08:58,040 --> 00:09:02,040 Speaker 1: do a whole episode about it. Anyway. There are also 142 00:09:02,320 --> 00:09:05,240 Speaker 1: a number of conditions that happen when the adaptive immune 143 00:09:05,240 --> 00:09:10,760 Speaker 1: system starts confusing your own cells for invaders. Every cell 144 00:09:10,800 --> 00:09:13,520 Speaker 1: in our bodies should be coded as self thanks to 145 00:09:13,600 --> 00:09:17,120 Speaker 1: antigens on the cell's surface. It's sort of like wearing 146 00:09:17,120 --> 00:09:20,840 Speaker 1: an id. Bad antigens tell your immune system at a glance, 147 00:09:21,120 --> 00:09:25,400 Speaker 1: hey I'm cool, I work here. There are entire processes 148 00:09:25,400 --> 00:09:28,480 Speaker 1: in your body to curate your T cells and B cells, 149 00:09:28,520 --> 00:09:31,080 Speaker 1: but keep their activity in check and make sure that 150 00:09:31,160 --> 00:09:34,120 Speaker 1: ones that seem to want to attack self codd cells 151 00:09:34,440 --> 00:09:38,160 Speaker 1: don't get into circulation in the first place. But it 152 00:09:38,280 --> 00:09:43,319 Speaker 1: still happens, and this category of conditions is called autoimmune disorders. 153 00:09:44,360 --> 00:09:47,880 Speaker 1: It includes things like arthritis, in which your immune system 154 00:09:47,920 --> 00:09:51,720 Speaker 1: attacks your joints, type one diabetes in which it attacks 155 00:09:51,720 --> 00:09:57,280 Speaker 1: your pancreas, multiple sclerosis which damages nerve cells, and psoriasis, 156 00:09:57,320 --> 00:10:01,439 Speaker 1: which damages the skin leading to scaly, pass or other problems. 157 00:10:02,480 --> 00:10:06,160 Speaker 1: Autoimmune disorders tend to be frustrating to treat, after all, 158 00:10:06,240 --> 00:10:09,560 Speaker 1: You can't just remove and replace a malfunctioning immune system 159 00:10:09,760 --> 00:10:14,280 Speaker 1: the way you might a kidney. Also, we don't understand 160 00:10:14,320 --> 00:10:19,360 Speaker 1: exactly why any given autoimmune disorder happens. There is a 161 00:10:19,440 --> 00:10:21,720 Speaker 1: lot of research going into this, and we've got a 162 00:10:21,760 --> 00:10:25,280 Speaker 1: lot of good starting concepts, but again, the entire immune 163 00:10:25,280 --> 00:10:28,040 Speaker 1: process is so complex that it's hard to nail things down. 164 00:10:29,400 --> 00:10:33,360 Speaker 1: For example, researchers have identified sets of genes that code 165 00:10:33,400 --> 00:10:37,360 Speaker 1: for things like how your immune cells recognize antigens or 166 00:10:37,679 --> 00:10:41,880 Speaker 1: how your body's cells produce their self ID. It makes 167 00:10:41,920 --> 00:10:44,800 Speaker 1: sense that errors in this coding could lead to problems. 168 00:10:46,000 --> 00:10:49,160 Speaker 1: Other research has looked into malfunctions in T cells that 169 00:10:49,360 --> 00:10:52,800 Speaker 1: lead them to overproduce those signal molecules that call in 170 00:10:52,840 --> 00:10:56,240 Speaker 1: the troops, which also leads to inflammation, which tends to 171 00:10:56,320 --> 00:11:00,520 Speaker 1: be an issue in autoimmune disorders. Yet other research is 172 00:11:00,600 --> 00:11:03,480 Speaker 1: diving in two malfunctions in a subset of T cells 173 00:11:03,600 --> 00:11:07,400 Speaker 1: called regulatory T cells, that are supposed to regulate their 174 00:11:07,440 --> 00:11:10,360 Speaker 1: fellow workers in the immune system, shutting down the red 175 00:11:10,400 --> 00:11:15,559 Speaker 1: alert after an infection has been cleared, and suppressing excess activity. 176 00:11:15,640 --> 00:11:17,880 Speaker 1: Even when we do have a decent idea of what's 177 00:11:17,920 --> 00:11:21,480 Speaker 1: going wrong, immune disorders of all types can be difficult 178 00:11:21,559 --> 00:11:26,120 Speaker 1: to treat, but there are increasingly effective therapies that can 179 00:11:26,200 --> 00:11:30,640 Speaker 1: ease symptoms or even target particular immune system activities to 180 00:11:30,679 --> 00:11:34,640 Speaker 1: help bring it back closer to normal. As always, if 181 00:11:34,720 --> 00:11:38,559 Speaker 1: you or a loved one is experiencing strange inflammation or 182 00:11:38,600 --> 00:11:42,640 Speaker 1: other irritating or painful symptoms with no obvious cause. You 183 00:11:42,720 --> 00:11:46,360 Speaker 1: know you didn't stub your skin, definitely get in touch 184 00:11:46,440 --> 00:11:49,320 Speaker 1: with a healthcare professional. They'll be able to help you 185 00:11:49,320 --> 00:11:52,840 Speaker 1: get a diagnosis and a treatment plan, even if your 186 00:11:52,880 --> 00:11:56,120 Speaker 1: body is a supervillain's layer that may or may not 187 00:11:56,320 --> 00:12:03,640 Speaker 1: be haunted. Today's episode is an original written by me. 188 00:12:04,240 --> 00:12:06,520 Speaker 1: Brain Stuff is production of iHeart Radio and is produced 189 00:12:06,520 --> 00:12:09,880 Speaker 1: by Tyler Klang. Four more podcasts from iHeartRadio visit the 190 00:12:09,920 --> 00:12:13,160 Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your 191 00:12:13,160 --> 00:12:13,920 Speaker 1: favorite shows.