What follows isn’t even close to a comprehensive overview of the immune system, because I am not a masochist, and because no one wants to read a 75,000-word story. Instead, I asked a few immunologists to chat with me about some of their favorite immune cells and molecules, and imagine what these disease fighters might be like if they truly were single and ready to mingle.
As it were, everyone needs someone to be their starter bae.
Some good candidates might be found among the members of the innate immune system, a fast-acting fleet of cells that are the first to contend with an infection. (Antibodies belong to another branch, called the adaptive immune system; more on that later.) They’re a lot like adolescent lovers: dogged and earnest, but impulsive and, on occasion, woefully imprecise. Unlike antibodies, which can zero in on specific pathogens, innate immune cells are built to clobber just about anything that doesn’t resemble their human host. Perhaps it’s no surprise that these underdog cells are often forgotten or outright snubbed in conversations about immune protection.
But the all-purpose approach of innate immune cells has its charms. They’ll try anything at least once, and they’re admirably selfless. When pathogens come knocking, innate cells are the first to volunteer to fight, and often the first to die (RIP, neutrophils). Some ambush invading microbes directly, snarfing them down or bathing them with deadly toxins, while others blow up infected cells—tactics reminiscent of guerrilla warfare. Although antibodies take many days to appear, innate cells will immediately be “by your side when you have a problem,” Ashton Trotman-Grant, an immunologist at the University of Toronto, told me.
These acts of martyrdom buy the rest of the immune system time to prepare a more targeted attack. And in many cases, innate immune cells act so quickly and decisively that they can subdue an invasive microbe on their own—a level of self-sufficiency that most other defenders can’t match.
Some innate immune cells are also just plain adorable. Among the fan favorites are macrophages (“big eaters” in Greek), aptly named for their round-boi physique and insatiable appetite. Their goal in life is to chow down for the greater good. “They’ll never make you feel like you’re eating too much, and they’re open to trying new foods,” Juliet Morrison, a virologist and immunologist at UC Riverside, told me. They’re also endearingly unselfish: If a microbe crosses their path, they’ll gobble it up, then belch up bits to wave at adaptive immune cells as a warning of potential danger. It’s a great gift-giving strategy, Morrison said, especially if weird microscopic puke is what makes your heart go pitter-patter.
Dendritic cells have a similar modus operandi. Like macrophages, they specialize in regurgitating gunk for other immune cells. But they are much more social than macrophages, which prefer to gorge and digest in solitude. Dendritic cells are sentinels and gregarious gossips; their primary imperative is to “talk and hang out with other cells,” and they’ll flit from tissue to tissue to do it, David Martinez, an immunologist at the University of North Carolina at Chapel Hill, told me. If you’ve recently caught word of a new and dangerous infection, you probably heard about it from a dendritic cell.