Illustration by John Phillips
Combatting a Constant Threat
Every second, our bodies must monitor a melange of threats that seek to invade and destroy. Scientists are just beginning to understand how the body's Command and Control Center tracks such a diversity of elusive enemies.
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Safety and security in the twenty-first century is more complicated than ever. In a terrifying new world of terrorism and cyber war, the threats are not just on the battlefield or countered with soldiers and guns. It’s often hard to separate foe from friend.
Our body experiences similar but vastly more complex challenges every day. And it has done so ever since Adam fell into sin approximately six thousand years ago. We may be impressed by the latest developments in counterterrorism, counterinsurgency, and counterespionage, promoted by Homeland Security and Cyber Command. But they don’t begin to match the know-how of the human body, which God designed to help us, even in the challenging world since the Fall.
These systems are up and running minute by minute, 24 hours a day, surveying our bodies for foreign invaders and following a series of pre-thought-out plans to protect us from ever-changing, life-threatening infections. We don’t have to supervise them—or even understand how they work—for them to be effective. Even with our latest technology, we’re still trying to unravel the secrets of this incredibly designed system that should be a constant reminder of God’s mercy.
The key to beating modern germs may be to understand how the two parts of the immune system were designed to work together.
Ever-Changing Threats
It is estimated that five billion different types of foreign agents are floating through the air, land, and sea, capable of entering our bodies and wreaking havoc at any time. Your own body is covered with ten thousand species of bacteria at any one time, totaling some 100 trillion individuals, though most are harmless. Every day, along with the air you breathe and the nutrients you ingest, you take in thousands of germs and potentially hazardous chemicals.
So the body needs to identify potential threats and remove them as quickly as possible. Yet it can’t afford to waste time and resources reacting to neutral or helpful substances. How does it identify threats and know when to intervene?
The challenge is compounded by the subversive nature of these forces. Unlike soldiers fighting on the open field under a single commander, they resemble terrorist cells that lack formal structure and work in secret. They take over by stealth, using sabotage (destroying facilities), espionage (stealing information), and subversion (making converts to their cause). To make matters worse, they learn from past mistakes and quickly adopt new technology.
This sounds like Al-Qaida, but it’s happening in the biological world. In the twentieth century, for instance, the virus HIV found a way past the body’s immune system, and by the 1980s it had reached epidemic proportions. Ever since, they’ve been at all-out war. As the body develops new tactics, HIV adapts in response.
Doctors are doing everything they can to fight such threats, but they can’t do it without understanding how the immune system works. Unfortunately, their research has been hampered by evolutionary assumptions. Most researchers assume the body’s immune system has two parts: a simpler system inherited from early ancestors, and a sophisticated system that evolved in “higher” life forms. For decades, researchers focused on the second line of defense and basically ignored the first.
Now they’re beginning to realize that the two work closely together. The key to beating modern germs may be to understand how the two parts of the immune system were designed to work together in a layered, integrated system. It appears that all the parts existed from the beginning and worked together in unison. This has all the hallmarks of elegant design. Despite efforts to evade the truth, the handiwork of the Designer can be “clearly seen” (Romans 1:20).
Illustration by John Phillips
First Line of Defense
The body’s immune surveillance system does everything covered in the United States’ $750 billion national defense budget, and a hundredfold more. It hires new personnel, continues training existing personnel, retires aging soldiers, funds ongoing and new operations, monitors old threats and identifies new ones, replaces worn-out equipment, and researches and develops new weapons and intelligence-gathering tools.
While the brains at the Pentagon and Washington struggle to coordinate multiple branches of the military and Homeland Security, your body does all this without your even thinking about it (except perhaps a few nudges to eat, rest, or care for a painful inflammation).
Passive Defenses—Barricades & Chemicals
The body’s defense begins with some physical and chemical barriers: your skin and the mucus on the lining of your eyes and lungs. These block invaders from entry or trap them in sticky mucus. Your skin, throat, nasal passages, and lungs also secrete antibacterial substances that kill invaders. In addition, your mouth produces saliva, and your stomach produces a pool of acid that kills indiscriminately. The liver is also constantly detoxifying chemicals.
Another surprising barrier in the first line of defense is “good bacteria,” which live on your skin and in your intestines. There they maintain safe, healthy environments so that foreign invaders can’t easily establish colonies. Like a well-manicured lawn, they prevent weeds from finding a place to take root. These good bacteria also shape their various environments to hinder foreign invaders (by changing pH, iron levels, etc.).
Last year scientists also discovered “good” viruses living in our mouths and on our gums, where they target specific bacteria that might otherwise make us sick. It seems clear that God designed our bodies to live in unison with various populations of bacteria and viruses, as long as they stay in their proper places.
Active Front Line Soldiers—Search & Destroy
A military’s frontline troops and their weapons are what everybody thinks of first when they talk about “defense.” The body has these, too—an army of billions of immune cells that it can call up for action within minutes. These troops possess at least 20 different exotic ways to kill or neutralize invading bacteria and viruses. White blood cells patrol our bloodstream and “eat” any cells that aren’t supposed to be there. These first-line defenders are called phagocytes (from two Greek words for “eat cells”). They are the real workers and heroes of the firstline defenses. They can stretch their membranes around foreign invaders and engulf them. In many cases they destroy the invader within seconds, using deadly enzymes or oxygen-based molecules like hydrogen peroxide and hypochlorous acid (the main component of bleach!).
Identifying Threats
The first law of armed conflict is to distinguish threats from innocent civilians and bystanders. Medical researchers are beginning to understand how important it is for the body to distinguish “self” from “other.” This is the key to understanding the human immune system and combatting modern disease.
Not every microbe is a threat. In fact, it is becoming more and more accepted that bacteria and viruses are very important to our body’s health. Along with the bacteria that help break down food in our digestive system, other bacteria help us manage our weight and many other crucial tasks.
Amazingly, God designed the immune system to distinguish good bacteria from bad bacteria, and it knows the checkpoints where they’re allowed safe entry (for example, your mouth). If bacteria break through another way, the body reacts instantly. If a couple hundred bacteria enter through a scrape in your skin, within hours you will notice a red, swollen, infected area. Yet if the same bacteria enter your mouth on the ham sandwich you eat for lunch, your body will tend to ignore them.
“Pattern Recognition Receptors” on White Blood Cells
So how does the immune system know what is a foreigner? And how does it know which foreigner is dangerous?
It turns out that every cell in your body carries a molecular “marker,” which your body can identify as “you.” They’re sort of like molecular fingerprints. Like an all-knowing Big Brother, your body constantly checks each cell or protein that moves through, looking for the right markers.
Many white blood cells have “pattern recognition receptors” that reach out and touch outside particles. If a cell passes inspection, it can move on. But if it is identified as “not you,” a whole new set of instructions come into play. The foreigner is now a suspect—marked for further investigation or instant destruction.
These white blood cells don’t carry around computerized photo ID banks and compare each cell to their list of photos. Instead, they rely on the “memory” within each of these “pattern recognition receptors.” They do this through white blood cells called phagocytes.
Until recently, researchers didn’t realize that phagocytes had this mechanism. They mistakenly assumed these cells evolved early and were less sophisticated, so they believed the cells roamed the body and almost indiscriminately killed or removed anything foreign. Researchers assumed the second-line defenders, which evolved later, were more sophisticated because they could study the enemy, adapt to their defenses, and prepare against future attacks.
But researchers have come to realize that these types of white blood cells simply serve different roles. They are closely related and work together to defend the body.
To identify threats, the first responders (the phagocytes) use the unique set of pattern recognition receptors, mentioned previously, to recognize anything broadly fitting the description of a “bacterium” or “virus.” Researchers have now catalogued a couple dozen receptors that recognize specific parts typical of any bacteria or virus. Some receptors recognize carbohydrates on the bacterial wall, some recognize the bacterial flagella (tails) and lipids (fats), and some recognize the DNA inside viruses. Amazingly, they “know” how to recognize these parts even before we’re born (and before we’ve been infected)!
The Lord has mercifully designed these first-line defenses to block or remove most threats, even without identifying specific new enemies. But if they fail to stop an invasion, more extreme “all hands on deck” responses must kick in—starting with inflammation, but eventually fever, vomiting, or diarrhea.
First-Line Defense—Fighting Infection
The body has many barriers, such as skin, to block unwanted invaders. When a cut opens a path for bacteria to enter, the immune system is ready with first-line defenders.
Illustration by John Phillips
Second Line of Defense
Even more amazing than the tactics, personnel, and weapons employed in the first line of defense is the body’s God-given ability to manage all these resources and develop new ones as needed.
The first line of defense, called the innate system, blocks enemy attacks with an elaborate arsenal of preexisting weapons which are triggered by the pattern recognition receptors. The second line of defense, called the adaptive (or acquired, or specific) immune system, does even more. It actually develops and tests new weapons, and then mass-produces the ones that prove effective. In addition, it retools manufacturing plants and builds new plants all around the body so that they can re-arm at a moment’s notice, should the enemy return.
Command and Control (T-cell Lymphocytes)
The workhorse of this system is another kind of white blood cell, called lymphocytes. These cells come in many forms, but the T-cell lymphocytes are the commanders. They do not engulf foreign invaders but instead confirm the identity of enemies, call for help, and coordinate defenses.
These cells communicate with all the other immune cells in the body and many tissue cells, warning them of infectious agents. Their options vary. If necessary, they can call forth an army of immune cells within minutes to surround and attack invaders. They also promote inflammation, which attracts various innate phagocyte cells to repair damage.
These second-line lymphocyte defenders begin life with a “blank slate” on their receptors. Like soldiers with bayonets fixed, they wait to be shown the identity of new biological threats. They are also equipped with a detailed operations manual that explains how to handle many different hostile situations.
How can this be? How does your body learn to recognize new enemies?
The secret lies in the fact that these specialized cells, the T-cell lymphocytes, work with a partner cell. This partner constantly picks up pieces of organic material in the bloodstream and uses its own receptor to “present” potential threats to the lymphocyte. And here is the amazing part: the partner cell constantly presents all the proteins it encounters in the body, even your own proteins, for inspection. The lymphocytes can then sense what is foreign by comparing it to what is “self.”
What a great system! In this way, everything can be accounted for. The T-cell lymphocytes start life with a clean slate and don’t consider anything to be “foreign.” Only with time do they learn what is dangerous. At first, the receptors react positively to all proteins in the human body, including many that come from other creatures, such as the bacteria that are needed in the stomach. Early in life, however, the T cells begin training in a special organ called the thymus to react against unwanted foreign invaders.
You can tell how important this ID system is by the problems that arise when it goes awry, labeling good things as bad. That’s what happens with autoimmune (“self–immune”) illnesses like diabetes. The body begins to consider its own proteins, which handle sugar, as an enemy. According to one theory, the thymus makes mistakes and fails to eliminate T cells that have gone rogue and attack “self.” These bad cells then enter the bloodstream and react against compounds that belong to “self.”
Research & Development (Antibodies)
The second line of defense also prepares the body against future attacks. To do this, the T cells call up a special type of lymphocyte, called a B cell. This cell’s mission is to design and mass-produce a weapon that will identify and tag these new invaders for destruction.
The B cell begins manufacturing molecules that conform to the shape of the invader’s molecular structure, like a lock and key. These molecules are called antibodies. Antibodies are specialized “tags” that automatically bind to any foreign biological substance that matches their shape.
Whenever an antibody binds to an invader, it sends out signals to nearby proteins, which assemble a round, hollow weapon that looks like a life preserver. Technically called a membrane attack complex, this ring is literally a mobile “bullet hole” that makes holes in the invader. Instead of a gun shooting a bullet into the cell, this ring skips the gun part and attaches directly to the invader’s cell membrane. These “bullet holes” also send out another signal to nearby phagocytes, summoning them to attack and consume the wounded enemy.
There are literally trillions of different possible variations of antibodies. The body’s ability to produce so many targeted weapons systems is another amazing aspect of the immune system. The human DNA codes for only about 20,000 proteins, yet your body can make a trillion different antibodies (a form of protein). How is this possible? This is the only known case where human genes are actually shuffled and sections are rearranged slightly to make unique, new proteins. The body carefully manages this “research and development” until it finds a combination that works.1
Preparation for the Next Attack
Antibodies are lifeless molecules, not living cells. They float freely in the blood system, sometimes for years, like smart sea mines waiting to attack a passing enemy ship. Literally billions of antibodies are found throughout the human body in almost all of its fluids. Together with the phagocytes, they patrol the body in its minute-by-minute first line of defense.
The B cells that produce the antibodies can “remember” the germs that cause an infection for many years. They do this by multiplying in great numbers after the first exposure to a foreign invader. They then spread throughout the body and stand ready to manufacture more antibodies at the first sign of a returning invader. While it can take up to 14 days for a B cell to manufacture an antibody the first time, they take only 2–3 days the second time.
These sentinel B cells explain why certain diseases, such as chicken pox and measles, can never re-infect you. Other diseases, such as the cold or flu, are more adaptable. Our defenses may stop them for a short time, but eventually they find a way to change their chemical markers to evade our system, and the war starts all over again. (That explains why you can’t catch the same cold twice; but you can catch a new cold soon afterward.)
Truly, the body is masterfully designed by our Creator God to take on any new threats in a fallen world, no matter how insidious they might be.
Second-Line Defenders—Fighting the Common Cold
When invaders get past the body’s first line of defense, the immune system calls up the second-line defenders. They eliminate the immediate threat and prepare for future attacks.
Did We Need Our Immune System Before the Fall?
When did God give us such an exquisite immune system if there was no disease, illness, or death before Adam’s Fall?
Creationists have long considered two options: the immune system was dormant in Adam and Eve and began functioning after the Fall, or it was added to the human body after the Fall. But there is a third option.
The biblical evidence does, indeed, show that some living things were modified in some way after the Fall. Mothers now experience pain in childbirth, and a snake’s body was altered to crawl on its belly. However, these cases do not appear to involve a “new” creation but a negative alteration of existing things, because of sin.
Genesis 1 emphasizes that the Lord completed His work on Day Six and then rested. So it seems most likely that the immune system was already performing an important function at creation, but this changed slightly after the Curse. Research by creation scientists, for example, is showing that plants may have produced thorns from preexisting genetic programs that produced something else before the Fall, such as small harmless “prickles” or leaves. Something similar is likely the case for the immune system.
What was its role before the Fall? Your body needs to be aware of everything going on around it. So the immune system appears to be a filtering system designed to monitor and control what goes into the body.
Think of the filtering systems in your car. Dust and dirt are not bad things in themselves (flowers need them to grow!). But a car is not the place for them. Car filters are designed to prevent dust and dirt from getting into the car engine, not because dirt is evil but because it needs to be kept in its proper place. The same seems true of the immune system.
The immune system has both a general purpose and a very specific purpose. First, the general filter keeps everything out that is not supposed to be part of the body. The mucus and other general barriers filter most small molecules. Second, the specific filter helps retain and promote the growth of beneficial microbes, while filtering out the rest. It does this by touching and feeling mainly microbes and distinguishing what is foreign versus what is “self.”
After the Fall, the general barrier continued to perform its job well. But for some reason, the specific part of the immune system sometimes reacts too strongly to foreign objects. There are several possible reasons.
- Perhaps some things that the general system once filtered out have been altered and become noxious. Pollen, for example, would have been harmless before the Fall and could easily have been filtered out by the general system. But after the Fall, dust and pollen may contain protein, fats, and DNA molecules that were altered to resemble microbes. The specific immune system recognizes them and reacts strongly.
- After the Fall the immune system lost some of its exquisite fine-tuning control and became overly aggressive, resulting in allergies and inflammation.
- Another possibility is that the potent aspects of the immune system, which were originally designed to keep out occasional exposure to strong chemicals or multicellular animals, became magnified over time, as they encountered more and more harmful things.
God placed Adam in a dynamic, interactive, molecular-based world that was “very good.” A filter like our immune system would be an elegant way to keep out unwanted dirt and nurture helpful microbes. Only after the Fall did our immune system add “defense” to its workload.
Why Are Allergies Increasing?
For several decades, researchers have noted that asthma and certain other autoimmune disorders, such as Crohn’s disease and multiple sclerosis, are increasing in developed countries as opposed to developing countries. How can this be, with all our emphasis on sterile, germ-free living?
The answer may lie in the nature of “autoimmune disorders”—diseases in which the body’s immune system fails to recognize self and attacks its own cells and tissues. The health data and trends suggest that early exposure to microbes is critical to a properly functioning immune system. Even in developed nations, children raised in farm country have much fewer allergies than their city counterparts. One report showed that family doctors who treat children raised on Amish farms in Indiana note that allergies are almost nonexistent in these communities.
These observations led to the hygiene or “lost friends” hypothesis. It suggests that children exposed to microbes early in life suffer from fewer autoimmune and allergic disorders later in life. Several findings seem to support this hypothesis. Breast-fed and natural-born children have fewer allergy disorders later in life compared to bottle-fed and C-section-born children. Recent studies have also shown that heart disease and even mental disorders are less frequent in individuals exposed to viruses and parasites early in life.
In a large study in Uganda, children born from mothers who were given antibiotics for a parasitic worm were more likely to suffer chronic skin inflammation in childhood. In fact some doctors are now treating autoimmune disorders like multiple sclerosis and asthma with small parasitic worms (don’t try this at home)!
What could be going on?
It appears that the T-regulatory cells (the supreme commanders of the immune system that keep the other immune cells in check) are stimulated to develop in great numbers when the human body is exposed to microbes early in life. If they miss out, the T-regulatory cells do not develop in great numbers, allowing the subordinate cells to operate out of control.
Without master commanders running the show, the immune system can begin to attack the body or overreact to environmental conditions, leading to allergies and asthma—more proof that there was an elegant balance of human body systems with the environment in God’s original design.
, chairperson of the Department of Biological and Physical Sciences and Department of Mathematics at The Master’s College, earned his PhD
from Wayne State University and completed a post-doctoral fellowship at the University of Michigan Medical School. He also teaches for Liberty University Online.
Answers Magazine
October – December 2014
This issue explores the marvelous human immune system. Plus take a look at the Creation Museum's new Allosaurus.
Browse Issue SubscribeFootnotes
- This gene shuffling is not an example of random genetic evolution. It is a very complex, pre-designed process—carefully guided by many specialized enzymes—to produce a specific goal: shuffle and splice genes to make new combinations of proteins (antibodies) that will combat germs.
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