Understanding Convalescent Plasma in Treating COVID-19
COVID-19 is being a big jerk. Not only is it slowing our pace of life, halting our economy, making thousands of people very sick, and stressing us all out — it’s also a tricky virus to treat and is killing thousands of people each day. This is why convalescent plasma is becoming a clever, natural way to kick this virus in the face.
If you didn’t already know, your blood is an amazing operator. Red cells are smarter than you. They are. They carry what you need to operate your brain, your heart, your entire system. EVERYTHING! Your blood is not just a trigger in a horror film, it’s something we all have in common. We all bleed red. In your blood are secret operatives working around the clock to fight for you. You have soldiers and superheroes ready at any moment to save the day. It’s an impressive power of your blood in combating illness.
How many times have we had a cold or caught the flu in our lives? Everyone gets the occasional cold during the year. We have a basic idea of what we need: tissue, soup, orange juice, warm hugs, and time. Our bodies have been introduced to different colds and flus over time. Because of this, our body knows how to respond. However, this coronavirus is something new to us, that’s why it’s so contagious. One of the biggest hurdles we are facing is the spreading and treatment of the disease.
Let’s journey back to tenth-grade biology class and talk about the basics of the blood system… and apologies up front for getting a bit sciencey.
As you probably remember, the two main components to our blood are red blood cells and white blood cells. The function of our red blood cells is to deliver oxygen to our organs and brain. They keep our machinery running smoothly, running a marathon with no set finish line. Our white blood cells have a very different role. Their job is to search for invaders in the body. They are incredible detectives — even smarter than Sherlock Holmes.
Our white blood cells can be divided into neutrophils and lymphocytes. The neutrophils are our town criers in the fight against viruses. It’s their job to search out invaders in the body — anything that looks suspicious. These tiny whistle blowers would be the first to recognize there was something usual going on. When they see anything unusual, they send out a signal, or basically get on their walkies talkies and alert the lymphocytes that something’s not right.
Our lymphocytes hear the call. Our T lymphocytes are the ones with the bazookas or tanks — our ‘T’-ank cells search and destroy. They hold the big guns and do a lot of the heavy lifting. Our B lymphocytes are basically our field photographers, taking a picture of the raging battle and passing along the mug shot alerting the body to “watch for this guy.” They do this to create antibodies. B lymphocytes also have a perfect memory, so when they encounter such an invader again, they know their enemies’ exact vulnerabilities and destroy them before they can do any damage.
This is how our antibodies are formed. This is a natural defense that our bodies create for us to survive.
Unfortunately, in the case of this novel coronavirus, our human bodies don’t remember seeing anything like it before. Seasonal colds or flu viruses are common so our immune system is well acquainted with them. But this corona guy is new “novel”. In symptomatic COVID-19 cases, the neutrophils haven’t been recognizing the virus as an invader until the system is overwhelmed, because they have no reference of virus patterns like these. The lymphocytes are quick to act once they hear the call to action, but it takes time to build up the numbers to defeat it.
When fighting off a virus like the novel coronavirus, the body produces Immunoglobulin G (IgG) antibodies. This is the mug shot we are looking for— the proof that the B lymphocytes did their job. This is the evidence we need in order to see and recognize that a person has truly beat the virus.
Our antibodies float in the plasma part of our blood. Blood plasma is the liquid component of the blood. That’s where you would find the IgG antibody. When we receive a vaccine, our bodies create this immune response and make antibodies against the disease, preventing us from contracting it. Scientists around the world are racing to develop one (1), but it may not be as fast as we all hope.
So, what is convalescent plasma and why is it important? “Convalescent” refers to someone who has recovered from an illness. Here’s how convalescent plasma can be used in fighting the coronavirus: someone who has recovered from COVID-19 and now carries the antibody that fights it in their plasma can donate their plasma to be transfused into a current COVID-19 patient. The transfusion would boost the patient’s immune response with soldiers already armed for battle, teaching the younger soldiers how to fight the monster of COVID-19. It comes in with tanks and guns loaded and ready for action.
The use of convalescent plasma is not a new idea. The FDA cites several times where its use has been approved, as recently as SARS, MERS, and H1N1(2). There is also evidence of convalescent plasma having been used as a treatment in the 1918 flu pandemic(3). Each time it has been used as a treatment is a new endeavor of an investigational nature, since each new virus presents a new challenge in how we fight it.
What is miraculous about this product is that it’s natural. WE MAKE IT! This is what the body does. It takes care of things we can’t see. As I explained before, our immune response is slow to detect the presence of the coronavirus. Patients who can benefit from convalescent plasma are in a situation where the T lymphocyte tanks cannot keep up with the invaders and are losing the battle. Giving the patient convalescent plasma is like sending in reinforcements, surprising the attackers with a fresh new army up on the ridge of the mountain in the eleventh hour (Lord of the Rings style). The reinforcements help rescue that tired army and the desperate patient from a fight they could not win alone. Who wouldn’t want an ending like that?
Collection of convalescent plasma is happening now. If you have donated platelets before, the process is much the same. The technique is called apheresis (4). Apheresis is where blood is collected from a donor through one needle, spun and separated into separate products (in this case plasma and red blood cells), and a second needle restores the red blood cells to the donor. And unlike red cell donation, a donor could donate more than one unit, possibly up to three to four units of plasma, enough to save a life or several lives.
The solution for COVID-19 is not simple, but understanding basic immunology is helping us fight the disease. We have billions of little soldiers ready to serve when called upon. If you have recovered from COVID-19, please contact your local donation center or the American Red Cross to see how you can help. You have superheroes inside of you right now ready to join the fight.
References:
- World Health Organization. Public Statement of Collaboration On COVID-19 Vaccine Development. https://www.who.int/news-room/detail/13-04-2020-public-statement-for-collaboration-on-covid-19-vaccine-development
- Food and Drug Administration. Recommendations for Investigational Use of COVID-19 Convalescent Plasma. https://www.fda.gov/vaccines-blood-biologics/investigational-new-drug-ind-or-device-exemption-ide-process-cber/recommendations-investigational-covid-19-convalescent-plasma
- Epstein, J. Potential Use of Convalescent Plasma During a Flu Pandemic, FDA ICDRA 2008 WHO.int
- MedicineNet. Apheresis. https://www.medicinenet.com/hemapheresis/article.htm
Disclaimer: the author currently works on the laboratory side of transfusion medicine. She is not affiliated with the American Red Cross.
