We had a lecture today on the topic of the immune system. The professor talked about all the different types of white blood cells, and what their individual jobs are during the immune response.
At some point, she must have said something about Neutrophils being the front lines. She must have. Because my brain instantly went into Analogy Overdrive. Marines! They’re like the Marines! I thought. As she explained more and more about the cells, the analogy just kept on going. I kept waiting for her to say something that was going to destroy the whole story, but she never did. It just worked.
After the class ended, I went to the professor and told her my new mechanism for understanding cellular immunity. She’s a fellow analogy lover, so I thought she’d appreciate another perspective. And she did appreciate it. Right after she got over the shock that it was an analogy that I’d thought up all on my own. Which took a while. Anyway, she asked me to write it all up in an email and send it to her.
I went through three phases in response to this request. Phase one was filled with thoughts like, “OMG, am so awesome. Teachers love me, la la la. During phase 2, I realized that I have no time. Certainly not enough time to be explaining elaborate immune-military reconnaissance missions to my med-surg professor. I complained about this duty during phase 2 to a classmate. I said I needed to be studying instead! She said, studying what? I was like, THE IMMUNE RESPONSE. She said, um, writing that email is kind of like studying. That kicked me into phase 3. For the duration of that phase I was mostly like um, holy crap, am I really about to send an email to my professor telling her about an alternative way to teach material that I truly have no grasp on?
Luckily, the risk of making a fool of myself has never, not once, stopped me from doing so. Below is the very long, very nerdy, boring to most people email that I wrote my professor this afternoon. Mostly I’m posting it because my father-in-law is going to truly enjoy the bit about Eosinophils.
The Immune Response: This Means War. Cellular War.
Neutrophils – The Marines of the Immune Response. The primary role of the marines is to go into a new zone and complete the first 30-60 days of war. They’re the first men in, setting up camp, working on the front lines. Just like Neutrophils in the immune response. Elevated neutrophils indicates a brand new infection, just like the presence of the marines should indicate a brand new battle.
Then the Monocytes come in. These guys are the army. Specifically, they are the infantry. They are the second group on the scene, taking over what the neutrophils have been doing, but in a more large-scale, endurance-oriented manner. They are all attack-attack-attack, kind of in a general way. They’re not real picky. If you’re a foreign body that is present in an area after the Monocytes have been called to duty, you’re a goner.
When the army sets up camp, that’s when the Macrophages take the star role. They are the army, but transformed from the infantry into a group with a more permanent residence. That’s why they stick around so long, even after the battle has been long won. (Macrophages have been known to stay elevated in the body for up to 6 months after all other signs of infection are gone.) They’re the clean up crew. Overthowing a government (beating an infection) takes a lot less time than cleaning up after the war and building a new government. And that’s why the macrophages stick around for so long. Their job is to clean up (by eating!) all the debris and junk that’s left over after the good fight has been fought. Another time we see elevated macrophage levels is when the body has a chronic infection. This is like what we see when the army sets up a full-blown camp whenever the war has taken a more “chronic” turn. We’re seeing the guys in Iraq and Afganistan do some patrolling, some rebuilding, and some general “cleaning of the streets” right now, similar roles to what the macrophages do weeks/months post-op. Only the soldiers aren’t eating the trash. Which is good. Seems like that would cause indigestion.
The Lymphocytes are kind of The Generals of the immune reaction. They show up after everything’s already a wee-bit settled in the immune response much like the generals wait until the more acute danger has passed before arriving in the war zone. Then they play the role of coordinating the T-cells and the B-cells. It’s their job to recognize the intruders/insurgent and point the armies of the immune system in the correct direction. Plus, they’re the “stars of the immune response,” right? Without the Officers/Bosses, the immune response is a little bit like the soldiers rushing onto the beach at normandy. They just went on the beach and killed everyone that they recognized as foreign. Then, after the craziness dies down, the Generals come in, start to help the soldiers focus their attack on a very specific group, just like the Lymphocyes help focus the attention of the immune response.
If you want to continue with the analogy, the Navy would have to be the T-helper cells. They often play the wartime role of managing the transportation, feeding, supplies, and general care of the men on the ground. In certain situations, the Navy does see some combat, but it’s not as often. And it’s very rare that the Navy runs into an attack like the Marines and Army. (They have planes and ships for that.) The T-helper cells don’t play a primary attack role in the immune response, either. They’re helpers. They help grow T-cells, and basically work to maximize the capabilities of the other cells by doing anything they can. As far as I know, the T-helper cells don’t have nukes, though, so that analogy might break down right there.
Eosinophils are a highly specialized type of cell that are activated when the body is having an immune response triggered by allergies. As we all know, our bodies aren’t always our friends with it comes to allergies. My body, for instance, thinks that Zack is an invader that needs to be stopped, lest he harm me. So I don’t have to elaborate much more before it becomes obvious that Zack and his dad both will feel that Eosinophils are the Air Force of the immune response. Highly specialized, usually misguided. Bonus similarity between the two: they’re both known for taking short tours.
And down here at the end, that only leaves the poor, lonely old Basophils. With their limited fighting capabilities and their primary role being listed as “carriers of stuff,” I’d have to guess that they’d best fit into the role of the Sea Bees. Both could be defined as: A support crew that doesn’t kill anything. Plus the Sea Bees surely had to be dedicated “carriers of stuff” when they were helping with the construction of the Panama Canal, which is the singular thing I know about the history of the Sea Bees. Sounds like a match made in heaven.