Vitals and Bits #7: The Phagocyte
One liter of my blood harbors 6 billion:
a. Red blood cells
b. Molecules of alcohol
c. Professional phagocytes
d. Estrogen particles
e. Undocumented workers
If you answered C, you’re correct! Yay! Now collect your prize and keep your trap shut whilst I drop some knowledge on you.
Phagocytes are white blood cells that eat bad things like bacteria or dangerous substances. The ability to engulf harmful invaders means that phagocytes play a crucial role in immunity.
Many cells can perform phagocytosis (or the act of engulfing a foreign substance), but that’s not their primary gig. A professional phagocyte, on the other hand, is much like a competitive eater in that its only job is to ingest nasty stuff.
In the human body, professional phagocytes come in several different flavors. These include the roving monocyte, the voracious macrophage, the badass neutrophil, the flashy dendritic cell and the multitalented mast cell. These cells are able to sniff out the bad guys by sensing the chemical signals of invaders like bacteria. Damaged or dying body tissues also release chemical signals that alert phagocytes to move in and help with the cleanup effort. In this way, phagocytes facilitate healing and repair.
Not all invading organisms are vulnerable to phagocytes. Like Jonah sitting inside the whale’s belly, some bacteria have learned to actually live inside the phagocytes that eat them. Others have learned how to evade or injure phagocytes.
Generally speaking, though, the ability to phagocytose, or eat, is a fundamental prerequisite to life. Cellular ability to phagocytose evolved early on in the tree of life and has been incorporated into nearly every single life form since then.
You’ve probably touched a few million of your own phagocytes if you’ve ever popped a juicy zit. Pimple pus comprises a bunch of neutrophils that have eaten bacteria and then died, along with a bunch of dead macrophages that have eaten the dead neutrophils. Phagocytes eating phagocytes! I love it.
I feel a particular affinity for my phagocytes, given our mutual love of bingeing. I daresay my diet of cupcakes and merlot is a tad more delicious than the professional phagocyte’s diet of bacterial toxins and dead tissue. But to each her own, I suppose. Bon Appetit!