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Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey

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Speaker 1: brain Stuff, Lauren Bogle bomb here. Antibodies and antibody tests

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Speaker 1: have been all over the news lately, so let's talk

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Speaker 1: about them. They're part of how your body defends itself.

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Speaker 1: But how do they work and why are we testing

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Speaker 1: for them? Your immune system is like an entire agency

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Speaker 1: in your body that's dedicated to keeping the bad guys

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Speaker 1: at bay in order to effectively destroy the enemy or

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Speaker 1: antigens as they're called in the immune system BIZ. The

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Speaker 1: agency has two arms that ideally work together. The innate

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Speaker 1: immune response acts very quickly but without much of a plan,

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Speaker 1: and the adaptive immune response is slower but much more

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Speaker 1: specific and effective and needs to collect data in order

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Speaker 1: to work. Our innate immune response includes a lot of

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Speaker 1: initial defensive barriers like your skin and nose hairs, as

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Speaker 1: well as a few all purpose weapons like natural killer

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Speaker 1: cells or NK cells, which cruise around the body destroying

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Speaker 1: cells infected by a virus and keeping an eye out

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Speaker 1: for tumors. Our adaptive immune response, on the other hand,

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Speaker 1: is the branch of the immune system that learns as

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Speaker 1: much about the enemy as possible and creates specialized weapons

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Speaker 1: to destroy it. Antibodies are an important tool of the

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Speaker 1: adaptive immune response. So what are they? Antibodies are y

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Speaker 1: shaped proteins that your immune system makes to help flag

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Speaker 1: foreign substances that the body has deemed harmful. Specialized immune

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Speaker 1: cells called plasma cells produced them. Plasma cells are activated

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Speaker 1: b cells, which is a type of cell that becomes

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Speaker 1: activated when one of its receptors recognizes an antigen or

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Speaker 1: an enemy and then binds to that enemy. They're then

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Speaker 1: poised to create a lot of antibodies for that enemy.

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Speaker 1: We spoke by email with Amrat Barber, a professor of

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Speaker 1: biology in the Department of Biological and Environmental Sciences at

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Speaker 1: Virginia's Longwood University. She explained Antibodies are found in your

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Speaker 1: blood and other tissues of your body, and they bind

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Speaker 1: to substances that appear foreign and dangerous to your body.

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Speaker 1: They are very specific and can recognize and bind to

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Speaker 1: many types of pathogens, including viruses, bacteria, fungus, and other

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Speaker 1: infectious agents. Your body has billions of antibodies, each recognizing

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Speaker 1: a different pathogen, and similar to a key and a lock,

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Speaker 1: an antibody is incredibly specific for the pathogen it recognizes,

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Speaker 1: so Your immune system has a key on its key

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Speaker 1: chain for each and every antigen it's ever fought. When

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Speaker 1: an antibody binds to the pathogen that it's specific for,

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Speaker 1: it acts as a flag to alert the immune system

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Speaker 1: that this antigen is dangerous and should be destroyed. The

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Speaker 1: antibody then works with other proteins and cells in your

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Speaker 1: immune system to slow the infection and clear the pathogen

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Speaker 1: from your body. A vaccine is made of defunct antigens

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Speaker 1: that show your immune system what the enemy looks like,

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Speaker 1: so that it can begin making antibodies to defend itself

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Speaker 1: against the pathogen before it's ever been exposed to the

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Speaker 1: real thing. Though, specific antibodies can sometimes wane and disappear,

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Speaker 1: which is why vaccine boosters are sometimes necessary. So that's antibodies,

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Speaker 1: But how do antibody tests work. An antibody test shows

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Speaker 1: whether a person's immune system has made antibodies against the

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Speaker 1: infection that's being tested for. If a person has been

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Speaker 1: exposed to a pathogen take the COVID nineteen virus, for instance,

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Speaker 1: then there be cells will become activated and start making

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Speaker 1: antibodies specific for that virus. But as good as antibodies

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Speaker 1: aren't their job. There's always a little lag time with

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Speaker 1: this process. It can take a week or two for

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Speaker 1: a person to start making antibodies against an infection with

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Speaker 1: particularly nasty pathogens like measles or even COVID nineteen. In

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Speaker 1: some cases, the disease might kill the person before their

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Speaker 1: immune system has time to develop antibodies against it. Barbara explained.

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Speaker 1: During an antibody test, a person's blood is analyzed to

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Speaker 1: see if it contains antibodies that bind to the virus.

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Speaker 1: It does not determine if someone has an active infection,

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Speaker 1: but whether they're making antibodies to the pathogen. A positive

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Speaker 1: antibody test suggests that the person was exposed to the pathogen.

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Speaker 1: In essence, an antibody test indicates that a person's body

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Speaker 1: has mounted an immune response against a specific pathogen at

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Speaker 1: some point, but what it can't tell is whether the

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Speaker 1: person is currently infected with that pathogen. There are different

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Speaker 1: types of antibodies for particular pathogens. Some indicate recent infection

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Speaker 1: and summer signs of older infection. Antibody testing means testing

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Speaker 1: for all of the different types. If you want to

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Speaker 1: look for a recent COVID nineteen infection, you'd test for

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Speaker 1: immunoglobin M antibodies. Immunoglobin G antibodies, on the other hand,

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Speaker 1: take longer to produce, so would indicate older infection. Current

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Speaker 1: COVID nineteen antibody testing can and does detect both types,

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Speaker 1: So a positive antibody test indicates that you have antibodies

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Speaker 1: in your blood that recognize and react with that specific pathogen,

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Speaker 1: which is a strong indicator that these antibodies would likely

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Speaker 1: provide immunity for some amount of time. In the case

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Speaker 1: of COVID nineteen, it's difficult to know at this point

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Speaker 1: for how long those antibodies can protect you from reinfection,

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Speaker 1: or even whether they can at all. Barbera said the

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Speaker 1: length of protection depends on a lot of factors, including

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Speaker 1: how much antibody a person makes and whether the virus mutates.

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Speaker 1: That said, antibody tests can be used not only to

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Speaker 1: determine if a person has been infected with COVID nineteen,

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Speaker 1: but also to gain a better understanding about how widespread

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Speaker 1: COVID nineteen is within a given community. For instance, people

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Speaker 1: who are infected with COVID nineteen but experienced relatively mild

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Speaker 1: symptoms will still test positive on an antibody test in

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Speaker 1: the same way as someone with a very acute case.

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Speaker 1: Barbara said, if antibody testing is conducted on a large scale,

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Speaker 1: the results can be used to more accurately estimate how

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Speaker 1: many people were exposed to the virus. Antibody tests will

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Speaker 1: also likely play a large role in getting life back

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Speaker 1: to normal. People with positive antibody tests will be able

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Speaker 1: to show that they developed immunity to the virus and

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Speaker 1: thus are protected from reinfection at least for an extended

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Speaker 1: amount of time. But Barbara warns that antibody test results

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Speaker 1: should be taken with a grain of salt, as people

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Speaker 1: who test positive may still have an active virus that

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Speaker 1: they could spread to others. Therefore, the use of a

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Speaker 1: test that tests for the presence of the actual virus,

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Speaker 1: paired with an antibody test for COVID nineteen would give

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Speaker 1: a more accurate picture of whether a person is safe

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Speaker 1: to return to normal life. Today's episode was written by

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Speaker 1: Jesscelyne Shields and produced by Tyler Klang. For more on

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Speaker 1: this and lots of other topics, because it houstof works

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