What is Antibody Testing?

What is Antibody Testing?

We are in a time of crisis. The entire world is under attack from a tiny microbe — tiny but deadly. Its name is Severe Acute Respiratory Syndrome Coronavirus 2 (SARS Cov 2), and it causes the disease Coronavirus (COVID - 19), which, as of today, has killed 300,000 people globally and has infected nearly 4 million people worldwide. It is a virus which enters the human body and makes its way to the cells in our lungs, forcing them to make more viruses. The virus also takes control of T-Cells. T-Cells are our immune cells which kill cancerous or diseased cells by ripping a hole in the cell membrane. The virus unleashes your T-Cells on your own healthy lung cells. The T-Cells eat away the healthy mucus lining on your lungs and leaves you vulnerable to other diseases such as pneumonia and flu. The heroes in times like these are the other cells in your immune system, especially one in particular: antibodies. Today, I will be talking about antibodies, antibody testing, and why they are vital in helping return to normal life after the coronavirus pandemic.

What exactly are antibodies, and what do they do? Antibodies are just one player in the vast and complex human immune system. The human immune system is a group of cells and organs which defends the body from foreign invaders. The Immune System has three stages: the innate defense system, the adaptive defense system, and the cell-mediated response. The first stage uses physical barriers like your skin and mucous membranes to prevent viruses from entering your blood. If your skin is bruised, your body calls in phagocytes, cells which, like fortress guards, swallow anyone suspicious and kill them with acid. If the phagocytes are overwhelmed, the body uses fever to burn everything. If the fever fails to prevent the viruses, the second stage begins. The second stage uses antibodies, like a wall of moving shields, to prevent viruses from entering cells. These antibodies stick to the receptors the virus uses to enter cells, forcing the virus to stay outside of a cell, making it an easy target for phagocytes. If the viruses enter the cell before the second stage, the third and final stage ensues. The third stage involves the T-Cells, like Seal Team Six, killing any cells which already have viruses inside them. If your immune system was a large fortress, the skin and mucous membranes would be the moat and fort walls, the phagocytes like the gate guards, the B Cells the soldiers in the castle, the antibodies the shields on the soldiers’ arms, and the T-Cells the elite guards of the royal family. If you ever mix up B Cells and T-Cells, remember: B Cells are your ordinary foot soldiers, but the T-Cells are the elite royal guards. 

Now, let me tell you a little more about the second stage, which involves B cells and antibodies. B cells grow and mature in the bone marrow. When they complete their training, they have several unique receptors on their surface. Each B cell bonds to only a certain type of virus. When a B cell bumps into the right virus, it fuses with it, fully activating the B cell, which then splits into many more clone B cells. These B cells then start producing Y-shaped proteins called antibodies.

Antibodies are the key weapon of the second stage of the immune response. When they come in contact with an invader, such as SARS Cov 2, they stick to the virus, marking it for death. Groups of antibodies often surround a virus entirely, making it impossible to enter a cell. It reminds me of my parents attempting to enter my room with all my Legos on the floor. Ouch. That must hurt. Because antibodies have several sticking points, like Legos, antibodies often clump several viruses together in a process called agglutination, making it harder for them to get around. This allows phagocytes to kill these large clumps. Because antibodies are created after you contract the virus, they can also be used to see who has previously contracted the virus.

In the past two months, doctors and researchers have been talking a lot about antibody testing. Antibody testing is used to check if someone previously had the virus. The main problem with COVID-19 is lack of diagnostic testing, which checks for symptoms of the virus. Due to substantial lack of tests, you can only get tested if you are over 60 years old or have a pre-existing condition such as diabetes and mild symptoms. Antibody testing is an alternative. If somebody had symptoms of the virus before but couldn’t get a diagnostic test before their symptoms subsided, they can get an antibody test to see if they had the coronavirus. Antibody tests can also be used to see whether there was a significant increase/decrease in the number of coronavirus cases after implementing a lockdown/reopening. The test itself is very simple. If the virus has successfully been repelled, there will be some antibodies in the blood and lymph. An antibody test samples the blood and exposes the sample to a piece of the coronavirus. If there are antibodies for the virus, the antibody will bond with the piece of coronavirus, sending off chemical signals which are detectable. However, if there are no antibodies, then there will be no reaction.

Antibody testing will help us turn the tide on the coronavirus. However, there are major problems with the testing. Only a few tests so far have worked accurately. Other tests give either false positives or false negatives. A false positive means that the test reports a chemical signal by the antibody bonding with the coronavirus when there really is no bonding. Sort of like how I bond with my brother. I don’t have one. A false negative means the test misses the signal. Another problem with the tests is that each and every antibody type in the body has unique receptors. No antibody type is the same. So a sample of the blood may not contain an antibody with receptors for the coronavirus, but the person as a whole may still have antibodies for the virus. As you can see, these tests are unfortunately not foolproof. However, there are many labs working to develop accurate antibody tests. For example, Roche Holdings, a Swiss biotech company, has an FDA approved 99.9% accurate antibody test available as of May of this year.

This antibody testing may not cure the coronavirus, but it is a vital factor in recuperation and return to normalcy. The testing will help avoid a second wave and quarantine people without immunity to the virus. Eventually, the antibody tests will be ready to use, and will allow us to more safely return to life as we knew it before the virus.