"OMG how is this so accurate???" an NPR reporter wrote to me in an email last night.
She had just taken the geekiest personality quiz I've ever seen. It's called "Which Immune Cell Are You?" It's by the biotech company Stemcell Technologies. And here on NPR's science desk, we've fallen in love with it. Because ... it's surprisingly good at nailing your personality.
You answer a series of questions about what you'd likely do in different scenarios. Some of the questions are easy, like "Which Netflix show are you most likely to watch after a long day of work?" But some are specific to working in a lab — so if you're not a scientist, you might have to finesse questions like "What's your favorite lab technique?"
Then the quiz gives you an immune cell identity, as well as a description of your personality. For example, my friend got this result from the quiz: "You find it difficult to leave your comfort zone, but once you do, you're amazed at what you're capable of."
And what cell is she? A monocyte, an immune cell with huge potential. It can turn into two other immune cells – a macrophage or a dendritic cell (learn more about them below).
During the pandemic, many of us have had a better appreciation for our immune system. Despite the media's obsession with antibodies, we've come to realize the immune system contains so many more components, called immune cells, which all help protect us from SARS-CoV-2.
Antibodies are the primary way your body stops an infection. But once you've been infected with SARS-CoV-2, the immune cells are critical for quickly clearing out the infection so it doesn't become severe and land you in the hospital. They also prepare you for your next encounter with SARS-CoV-2.
While the quiz matches up your personality to the cell, it doesn't say much about how these cells actually work inside your body. So here's a handy guide to some of the immune cells highlighted in the quiz.
Memory B cells
If you catch SARS-CoV-2, B cells manufacture antibodies to help stop the infection and prevent a future one. But after the infection passes, they don't simply forget about SARS-CoV-2. Oh no! Some of them prepare for the next encounter with SARS-CoV-2 by optimizing the antibodies they produce.
For several months after the infection, some B cells go through a training process in which they learn to make better, more potent antibodies.
If the cells successfully complete this training process, they become "memory B cells." They circulate in the blood – perhaps for decades – simply waiting to see if SARS-CoV-2 returns. If it does, they quickly snap into action, pumping out antibodies to stop the reinfection.
Macrophages
Macrophages are large cells that swallow up bacteria, viruses and damaged or infected cells. Their name literally means "big eater" in Greek. And they can clean up the death and destruction that can occur during an infection.
But macrophages are multifaceted. In many ways, they are leaders of the immune system, directing the action but also taking on whatever role is needed at the time.
They can help with tissue-repair and wound-healing. They can also hang out in tissues (e.g., nasal passages and throat), patrolling for signs of viruses. When they detect danger, they can recruit T cells to the scene — which can kickstart antibody manufacturing.
Macrophages are super powerful – and sometimes that power can be destructive. With COVID, there's evidence that in the lungs, macrophages trigger an inflammatory cycle that eventually causes severe and persistent pneumonia.
Helper T cells
When I took the quiz, I got helper T cell. At first, I was a bit disappointed. I wanted to be a dendritic cell (see below). But then after reading about helper T cells more, I realized: They are dope.
Here's why.
B cells manufacture antibodies, but they need help getting started. Helper T cells supply that help. They are the ones that say to the B cells, "OK team, we have a situation here and it's time for you to get going and begin pumping out antibodies."
They also wake up macrophages, which kill and eat up cells where SARS-CoV-2 is hiding out.
Dendritic cells
These are beautiful cells with long, finger-like projections that reach up into layers of tissue. Their main job is communication. They are great at gathering information about pathogens and then spreading the word to other immune cells.
Dendritic cells patrol the tissues, including the upper respiratory tract, looking for pathogens. When the dendritic cells find them, they rush and tell the T and B cells about the problem, and those two types of cells then work together to start making antibodies.
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