On April 3, the Washington Post reported some good news about COVID-19. A man named William “Bill” Lapschies celebrated his birthday — and his full recovery from the novel coronavirus. He took ill in early March and was one of the first confirmed cases in Oregon. On April 1, not a fools’ day joke in sight, his doctors declared him clear of the virus.
Bill Lapschies is — and will continue to be — 104 years old.
Meanwhile, also on April 1, news broke that Adam Schlesinger, songwriter for the rock group Fountains of Wayne, died of COVID-19 complications. He was 52 — exactly half Bill Lapschies’ age.
Every large statistical group has outliers, but in a pandemic that overwhelmingly targets older people, these two stories beg some oft-begged questions: How did Bill survive? Why did Adam die? What factors make some of us more fit, immunity-wise, than others — regardless of age? What does it mean if, for example, your partner or child gets sick and you don't — or vice versa?
We know that our immune system function declines with age. Doctors call it immunosenescence. It's slow and insidious; think of a photo of yourself 10 years ago versus one taken this afternoon.
"You see changes in your face, skin and hair color,” says Insoo Kang, M.D., associate professor of medicine and director of allergy, immunology and internal medicine at the Yale School of Medicine. “It takes time. Same process with your immune system."
Kang has been studying human aging for 20 years. “Immune cells, especially CD8+ T cells [a type of white blood cell], change with aging. We see fewer naive CD8+ T cells, which are needed to recognize newly emerging microorganisms like the COVID-19 virus. It happens to everyone on some level, just not at the same rate."
The difference in rate of decline between individuals is one of science's big mysteries. The immune system is complex, but most of us understand the basics: Our body detects an intruder — a virus, bacterium, parasite or foreign object — and produces white blood cells to combat the problem. How many of these cells you produce when you're, say, 73 versus when you were 45 is the million-dollar question — and it's at the heart of the COVID-19 pandemic as well: How does a 104-year-old man survive when people half his age, or younger, do not?
Fortunately, we won't always be in a pandemic. But we can use this one to gain an understanding of how our immune system changes with age — and how it might be possible to slow the decline and raise our immune reserves for the next time we get sick.
Terms to Know
- Immunosenescence: Natural tendency toward diminished immunity as we age
- Inflammaging: Natural tendency toward more inflammation as we age
- T cells: White blood cells that attack viruses
- B cells: White blood cells that make antibodies to fight infection
- Memory cells: T cells that “remember” past viruses and give us immunity to them
- Naive cells: T cells that “teach” themselves to fight new viruses, such as COVID-19
- Cytokines: Small protein molecules released by a variety of cells in the body that help regulate immune response and inflammation. When the immune system is dysregulated, the body can overproduce cytokines, causing inflammation and disease.
- Myokines: Immune-boosting, anti-inflammatory compounds released by muscle that bolster the immune system
Aging Effect No. 1: Fewer immune cells
Our body simply doesn't produce as many immune cells as we get older, says Atul Butte, M.D., distinguished professor of epidemiology, biostatistics and pediatrics at the University of California, San Francisco. “And no one really knows why."
Butte worked with a research team on an extensive review of 242 immunity studies that revealed patterns in how our immune systems change as we get older. Certain key immune cells — B cells and T cells, which are the virus fighters — become fewer in number with age. For example, we possess two different types of T cells: “memory” cells that have encountered a certain pathogen and “remember” how to fight it, and “naive” cells that have yet to fight anything. “We've seen especially that the number of naive T cells seem to be lower as we age,” Butte says.
So let's say COVID-19 shows up. Nothing we've seen before as humans matches this one, so we have no memory T cells to mobilize. The naive cells have to take on the fight, and older folks have fewer of those to fight with. That makes us more vulnerable.
Or rather, that makes most of us more vulnerable. The mystery of immunity decline is complicated by the fact that not everyone's immune system declines in the same way. For example, another factor Butte observed in his study review: Some healthy older people had little or no decline in T cells. Some had as many as younger people, and women seemed to have higher amounts in general as they aged.
Part of the reason B and T cells are so enigmatic is that no one really knows just what a healthy amount of B and T cells is. Says Butte: “If you want to have a test for your hemoglobin, they know what a normal range is. If you want your iron levels tested, they know what the normal range is. We have no idea what the normal level is for these cells. We don't even measure them in a regular blood test."
The reasons these key cells decline over time could be manifold: Our bone marrow produces white blood cells. Is that where the problem lies? Is it genetic? Lifestyle? An apple a day? All of the above? All immunologists can do is keep looking. “We know genetics plays a part,” Butte says. “But it's debatable how big of a part compared with environment and lifestyle."