I, the protective system that you call the “immune system,” am divided into different groups and sections, each of which has its own area of expertise. Just like a military unit, each of my groups has to be partially or fully trained before it begins life in my system so that it can properly fulfill its defensive function. “Soldiers” in this protective troop work according to what expertise they have and the type of “enemy” (alien microorganisms) they encounter. Some are equipped with heavy weapons against tough enemies; some produce a special poison with which they kill their enemies by injecting it into their bodies, some work like a waste disposal, smashing up the dead bodies of the enemies, and some of them eat the alien intruders alive when they attack your body. Others produce raw material to arm your body, some turn that material into weapons, some work as defenders, some are signalers, some are rangers and some are equipped with a special intelligence which allows them to recognize the previous invaders and destroy them more easily at their future encounter. In this intelligence system, which works like an information center, the soldiers check the dangerous invaders and remember their previous experience with them. Then, they develop a strategy to fight against those invaders. If the enemy is known well, the defense against it will be easier.

Now, using this analogy, I will talk about your enemies and the features of my soldiers that are placed in your body to fight against them. However, I have to remind you of something first: as you know, every army has to have a top commander. Similarly, there is someone who has placed such a perfect system like me in your body, someone who has boundless knowledge and power, and has no one else superior to Him or has no one to receive orders and instructions. That is our Lord God Almighty. Since He knows very well what kinds of enemies you will face, He has created me with all my troops so that you can be defended against those enemies.

The enemies of your body are germs, which enter your body through different passage ways, including digestion, respiration, excretion and the skin. “Germ” is a general term referring to many kinds of micro-organisms. Some of them are bacteria, some are fungi and some are viruses. Your body needs different special tactics to defend against each group of germs and my soldiers are quite talented in those tactics. I have to be always watchful against germs coming from outside. Not only that, but I also have to be careful about inner enemies, that is, the cells in your body which suddenly turn into “terrorists” becoming harmful and spoiling the system. You call those cells “cancerous.” It is a great challenge for me to cope with those cells because they originate from among your very own cells and they know our tactics very well. Nevertheless, with God’s help, we can defeat them. However, when too much stress and anxiety weaken me I might miss some of those cancerous cells, which will grow and become tumors. In fact, cancerous cells develop much more in number than is commonly known. But my soldiers constantly check every single cell that is formed in your body and try to see whether it is normal or not. As soon as they discover a cancerous “terrorist” cell, they try to quickly destroy it. However, some cancerous cells are disguised like a wolf wearing a sheepskin so that they can avoid detection. My soldiers make rounds and check the cells from outside by only looking at their skin. Thus, they can be manipulated. All of your cells, including those with germs or cancer, contain protein with a special code which identifies the cells as being yours. When my soldiers encounter our fellow cells carrying those coded proteins, they release them. But the enemies who do not carry this code (or password) are immediately caught and destroyed. When we have diseases like cancer, however, the cancerous cells may evade our “rounds man” because they know this password. Sometimes the opposite may happen: my soldiers get confused and cannot identify their fellow cells despite carrying the right password, assume that they are enemies and start to attack them. These types of diseases, called Autoimmune diseases, emerge with a quite complicated mechanism which is a puzzle even for me! For example, during rheumatoid arthritis, which is among the many long-lasting and unrecoverable diseases, my soldiers attack and gradually destroy the tissues like cartilage, cardiac muscle, eye lenses, and the tubes of the kidneys with which they share a body. In fact, when we are created as a whole system (when you are only an embryo in your mother’s womb), some of my soldiers make an agreement with the other cells of your body, announcing that they will forever stay friends with them, will show tolerance to them and will only attack the enemies. But, somehow this agreement is broken later; my soldiers do not obey me anymore.

Now it is time for my group of soldiers to introduce themselves:

The most general term by which we are identified with is white blood cells or leukocyte. We appear approximately 6,000 to 7,000 times in each cubic millimeter of human blood. The other blood cells, which are called red blood cells (erythrocyte) are red in color; it is for this reason that we are called white. Since blood vessels can reach to the remotest edges of the body, we roam around the body through those vessels and look for work to do. Of course, not everyone can do everything. So, we are first divided into two sections. The cells in the first section contain microscopic granules, so they are called granular leukocyte. The cells in the second section do not contain such granules, so they are called agranular leukocyte. Those sections are divided into groups among themselves. The first section has three groups: neutrophils, eosinophils and basophils. The second section has two groups named monocyte and lymphocyte.

Eosinophills: You may not know much about these soldiers that make up 12% of the whole protective body. However, during allergic reactions and diseases caused by parasites, the number of these soldiers increases. They complete the effect of the antibodies produced against the antigens. Some chemical substances like histamine appear as a reaction to antigens, such as itchiness, rash, and swelling. Eosinophils reduce the effects of those substances and the symptoms.

Basophils, which are the least in number, make up the 0.5% of the body. Those soldiers are present mostly in the scars that are healing or in highly infected areas. The granules inside basophils contain two very important substances called heparin and histamine. Histamine helps expand the blood vessels and accelerates the release of active substances within me from the blood vessel walls, enabling them to reach to the affected area. Heparin also prevents the blockage of blood vessels because of blood clot.

Lymphocytes of the second section are the group of soldiers which goes through special training and has expertise in many subjects. They make up 20-25% of the soldiers in my system. Those soldiers detect antigens and germs and remove them from the body. Every soldier has a detector which identifies a certain antigen. Therefore, in your blood, there are millions of lymphocyte soldiers, which are different from each other and do not have a pair. For any antigen of a germ, you will definitely find a lymphocyte that finds and kills it. Those soldiers can be grouped according to their appearances, as small, medium, and large lymphocytes. Each group has different special features. We can also divide them according to their maturation and training process as B-lymphocytes and T-lymphocytes. Although both of them originate from stem cells in the bone marrow, T-lymphocytes mature in the thymus before they move to the other lymph tissues such as the spleen, liver, and tonsils (Thymus is a gland in the chest that talked about itself in the previous issue). B-lymphocytes, however, mature in the bone marrow, and go directly to the tonsils, appendicitis, spleen and other lymph tissues. When the T lymphocytes mature in the bone marrow, they acquire different new features. Some of them work as T helper cell, some work as natural killer T-cells and some work as suppressor T-cell. A helper T-cell, which is triggered by an antigen that is specific to it, secretes lymphokines, which makes B-cells produce antibodies. Among those lymphokines, interleukin-2 activates the natural killer T-cells, which kill the infected cells. The killer T-cells do not bind directly to an antigen. Rather, they secrete a substance that kills the infected cell after joining with the antibodies that were previously bound to the infected cells. On average, T-cells live 2-4 years; some, however, live more than 10 years. Today, the defense mechanism of the T-lymphocytes creates an issue in terms of organ transplantation. If, for some reason, a foreign organ (a kidney or heart, for example) is transplanted into the body, the T-lymphocytes attack that organ immediately. Those “headless” soldiers do not know that the body really needs that organ and try to eliminate it, therefore, leading to transplant rejection or tissue incompatibility. The T-lymphocytes treat the foreign organ the same way as they do to the cancerous cells: they attack and try to destroy it. For this reason, the immunologists are trying to discover medicines that will help them control the soldier T-lymphocytes whenever they need to be stopped.

Dear Peter, have you ever thought about how all this happens? While you have no idea about a germ that might enter your body, those memory cells, which are placed in your blood with a boundless compassion by our Creator, remember an enemy that they saw years ago, and begin to make weapons right away. Since those cells are devoid of reason and consciousness, to operate them there has to be Someone with a great knowledge and will.

The lymph nodes are production centers for the lymphocytes found at some particular places in the body. They resemble variously sized military headquarters. The lymphocytes are produced mostly at infection sites, which are the little lymph tissue groups located under the epithelium that lines along the walls of the digestive tube, respiratory track, and the bladder. When fighting with bacterial infections the lymph nodes swell and enlarge as much as 1–2 cm. In addition to the lymph nodes that extend through the lymph vessels, the areas such as nape, groin and the axilla (underarm) also contain lymph nodes. If you get an upper respiratory tract infection, the lymph nodes at your tonsils and neck areas become swollen. If you get a urinary track infection the nodes in your groin area become swollen. As for digestive track infections, it is the responsibility of the lymphocytes in your appendix to fight against germs. Some scientists view this organ, which is an extension of the cecum (the blind gut), as a “dead” piece of intestine. Both the appendix and tonsils are quite useful organs that produce lymphocytes in normal circumstances; they are not some useless remnants. For that reason, it is not right to remove them when it is not really necessary. However, we have to remember the proverb that says, “We salt the food so that it does not smell bad; but, what do we do if the salt itself smells bad? Then, we have to get rid of the salt.” Similarly, in some bodies where my system is weak and so is lymphocyte production, those areas become home to germs and you have to remove them.

Other than the soldiers of the immune system, several organs in your body have their own ways of protecting your body. Those organs do not have soldiers like in my system; theirs are like a “civil defense.” Chief among those are your skin which works as a natural barricade against the entrance of the germs, the mucous membrane that lines along the walls of your mouth and inner nose, interferon which is a substance produced by your cells against viruses, and an antibacterial substance called lysozyme which exists in your tears and sweat. Therefore, sweating, crying, and runny nose are not things to be ashamed of; they are only the protective systems that have been naturally placed in your body by our Lord God.

Dear Peter, I think I should stop here although there are still so many features of me that you have to discover. After all, beneath all diseases and deaths you will find disorders related to me. The biochemical processes in which many of my soldiers operate are not exactly known yet. If those are revealed, doctors will likely succeed in healing many other diseases. However, sooner or later you will reach the destined end: death. No creation can be immortal; there will definitely be a problem and you will have to leave this world, wherein you are only a guest. If you carefully contemplate the works of art in your body, in the hereafter you will have solved the riddle of the delicacies of those works. Of course, everyone’s time of death is unknown. Therefore, in this limited time, give your organs their due and give thanks to the God Almighty who gave you those gifts. Live according to His will, and always remember to glorify Him. Goodbye, Peter! May you and your troop be healthy!

Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir, Turkey

Immunity can be divided into innate immunity and acquired immunity. The mechanisms of innate immunity are given to us by our Creator as a tool with which to protect ourselves. These are used to fight against every kind of microorganism. These ever-ready forces do not need to have met the enemy microorganisms to fight them off. Acquired immunity comes about after the infectious microbe has been encountered; this is usually as a result of infection or vaccination. Such immunities only protect the body against a specific harmful organism. T and B lymphocytes and antibodies belong in the acquired immune system, whereas other mechanisms are part of the innate immune system. We can classify the very intricate immunity mechanisms as follows:

A – Layers that cover the inner and outer surfaces of the body: These are the physical structures that carry out the task of protection by covering the tissues like a shield or fortress.

1. Skin: Our skin is an organ in its own right. It is created with such perfect characteristics that no microorganism can penetrate our body if there are no flaws, like gashes, scratches, or wounds.

2. Oral mucous membrane: If the epithelial layer covering the interior walls of our mouth is healthy, microorganisms cannot infiltrate the blood.

3. Areas around the sexual organs: The sexual organ in males is, even at birth, more protected than that of females. For female children, the epithelium covering the interior face of the organ turns into a multi-layered structure due to the impact of estrogen (sexuality hormone) that starts being secreted after adolescence. That multilayered structure blocks infections that can result from sexual intercourse. Female children before adolescence do not have estrogen, thus their genital organs have a thinner layer of epithelium and are more likely to be infected. This is why cleansing after urination should be done from the front to the back and the genital organs should not come into contact with feces. Our God of infinite mercy also gives girls a hymen in order to protect girls from germs.

B – Flora bacteria (beneficial bacteria): These do not serve as mechanical obstacles, but are assigned tasks. There are some bacteria that do not cause illnesses in the urine and in the proliferation canals, the skin, throat, intestines, and the eyes. Those beneficial bacteria located in our body work for us and hinder other infectious bacteria from settling in these zones. Those places are sterile in the body of a fetus; no beneficial bacteria exist there. Protector bacteria are positioned in those places right after the birth; this is a revelation of God’s infinite compassion. For instance, a baby’s first feces are sterile because there are no bacteria in his intestines. As time passes, a baby adopts protector bacteria through his mouth by nursing, from bottles, and pacifiers. Parents should be careful about the purity of pacifiers, feeding bottles, water, and additional nourishments, particularly in the first couple of months, until the bacteria flora have been established in an infant’s body. Otherwise, babies can easily suffer from diarrhea. God equipped beneficial bacteria with some special peculiarities to be able to deter other microorganisms from settling in the body. Here are some of these peculiarities:

1. They compete with infectious bacteria on the consumption of nutrients, so they restrain the reproduction of other bacteria.

2. They emit bactericides that kill only pathogenic (harmful and infectious) bacteria.

3. Some flora bacteria are assigned a mission to impede the reproduction of pathogenic bacteria so as to reduce pH (increase acidity) in the environment. For example, the lactobacillus in the female genital passage produces lactose by breaking down the glucose in the uterine canal in order to acidify the secreted matters in that canal. Reproduction of fungi is also obstructed in the same way. Due to that fact, some fungal diseases might emerge in genital areas or in the ears, among other places, after antibiotic treatment. Antibiotics kill not only pathogenic bacteria, but also flora bacteria. Thus, desultory usage of antibiotics should be avoided.

Today, beneficial intestinal bacteria are taken orally in capsules, and infectious bacteria in the intestines are killed by supplementing the flora bacteria in that organ without the use of antibiotics.

C – Mechanical cleansing:

1. Secretions:

a.Saliva: Secreted continuously from the glands behind the ears, beneath the chin and beneath the tongue, saliva expels the intruder pathogenic bacteria by cleansing our mouths. It also prevents tooth decay and gum inflammation by cleaning leftover food on which bacteria could feed.

b. Tears: Tears are charged with the duty of cleaning the conjunctiva (the mucous membrane that lines the inner surface of the eyelids and that continues over the forepart of the eyeball) and the cornea (the transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior).

2.Cilia: These are feather-like cell extensions of microscopic size.

a.Nasal Cilia: Covering the nasal mucous membrane, mucus (a slimy substance) grasps dust particles and microbes in the air due to its adhesive nature. Lumpy folds inside the nose do not let the air flow straight. Therefore, a turbulent air current occurs in the nose. This turbulent current causes the particles in the air to come into contact with this slimy substance and to get stuck there. Epithelial cells also have cilia expanding toward the nasal cavity. Every cell has nearly 200 cilia. These cilia push mucus and the dust particles attached to it toward the pharynx with an up and down whipping action (10–20 strokes per second) so as to keep them away from the lungs.

b.Cilia in the lower respiratory passages: The upper surface of epithelium that is spread on the trachea, bronchi, and bronchioles is also covered with mucus. Epithelial cells in this area have cilia, too. These cilia do the same whipping action to push particles and microorganisms in the mucus toward the pharynx. They are pushed into the pharynx and expelled by coughing. One of the damaging impacts of nicotine on the respiratory system is that it paralyzes these cilia and disrupts the discharging process of harmful particles. As a consequence, smoking leads to many lung diseases.

D – Enzymes, acids and antibodies in body secretions:

1.Lysozyme: This is a substance found in body secretions (saliva, perspiration, tear, genital organ secretion etc.) that kills bacteria.

2.Stomach acid (Hydrochloric acid, HCl): Being emitted through stomach glands, HCl is a strong acid that can destroy bacteria that are able to reach as far as the stomach with the food we eat. Although we usually have our meals without cleaning our hands sufficiently or without washing them thoroughly, we rarely (except for situations where we are exposed to a high density of microbes like food poisoning or dirty drinking water) get infected via this route. The actors in this perfect protection are lysozyme and stomach acid.

3.Antibodies: Being present in the blood and body secretions, antibodies play a role in the defense against microorganisms. Antibodies in breast milk are passed from the mother’s blood to her milk via a very special mechanism, and are significant in the protection of an infant from infections.

E – Defender Cells: Resembling special operation forces, each of these cells is trained in different parts of the body and sent into the blood circulation. Those troop-like cells, which protect us against diseases by struggling fiercely with germs that can reach the blood after overcoming many obstacles, cannot have come about merely by chance, without the participation of the All-Knowing Designer.

1.Macrophages: Monocytes, a kind of leukocyte in the blood, pass from the capillaries to the tissue and turn into giant cells called macrophages that can phagocytose (swallow microbes) at a great rate. Macrophages swallow and tear down every kind of bacteria and virus that invades the body. These cells constitute the first defense line of the body and serve like advance guards. For instance, the first force to start fighting against the germs that can penetrate the skin through a scratch is the macrophages found just beneath the skin are called histiocytes. Germs that can infiltrate the blood through the intestines and reach the liver via the portal vein are eradicated by another type of macrophage. Therefore, almost no bacterium can pass from the intestines into the general blood circulation system. Germs that enter the body orally are destroyed by macrophages stationed in the lymph nodes on the tonsils. The ones that manage to reach the lungs through the respiratory paths are killed by the macrophages in the alveoli. Those cells also cause T-lymphocytes (very specially equipped cells) to proliferate by stimulating them. 2.Neutrophils: These are the most common type (60-70%) of leukocytes. These cells participate only in fights against bacteria. When bacteria enter a tissue, some poisonous matters emitted by them cause a chemical reaction called chemotaxis; this reaction attracts the neutrophils toward the infected tissue. In this case, the neutrophils leave their capillaries for the infected tissue and find and destroy the bacteria. How can germ-eating cells, like macrophages and neutrophils, distinguish normal body cells from microbes? Undoubtedly, the Creator of such an excellent defense system does not make us worry about such a problem; it was for this purpose that God created opsonins. Opsonins are similar to adapters in that they are able to attach two different parts together and connect themselves to a specific place on the germ. Thus, macrophages and neutrophils carry out their germ-eating job perfectly, connecting themselves to those opsonins. Since our own body cells do not have receptors that can handle opsonins, they cannot be eaten. 3.Lymphocytes: These are the troops of the immunity system with the most complicated organizations and strategies. These troops are categorized as T and B lymphocytes. They are the most important and powerful of the immunity mechanisms and constitute about 20-30% of the leukocytes in blood. They are regarded as the last defense line against those germs with which the other mechanisms cannot cope. a.T lymphocytes: When T lymphocytes are stimulated by macrophages, T cells that are a form of T lymphocyte secrete a matter called lymphokine. Lymphokine stimulates cytotoxic (microbe killer) T cells and B lymphocytes into action. Unless auxiliary T cells exist, the acquired immunity system collapses. Likewise, the HIV virus destroys auxiliary T cells and renders a person susceptible to disease. Even very simple infections can turn into a catastrophe for those patients. Cytotoxic T cells assault bacteria and particularly virus-infected body cells. They deliver porphyrins (proteins to make holes) into cell membranes by attaching themselves to the cells. In that way, a huge amount of water enters the cells and they get torn, due to over-swelling. Thus, viruses in the infected cells are dispersed and are neutralized by specific antibodies produced for that purpose with their infecting ability being impeded. (Viruses have to enter body cells to be able to proliferate. Only in this way can they protect themselves against antibodies and proliferate. Viruses that proliferate in cells use matters in those cells and cause them to eventually break apart, then move onto other cells.) b.B lymphocytes: These cells are stimulated directly by microbes. However, they need lymphokines to be completely stimulated and activated. Lymphokines are created capable of causing B lymphocytes to proliferate and transform themselves to Plasmocytes. Plasmocytes also emit antibodies to the blood. c.Killer cells: These play a role in the innate immune system, so they do not need stimulation like T and B lymphocytes. In particular, they assault body cells that are virus-infected or show a tendency to cancer. In this way, they establish a first defense line against viruses and block cancer development. Even though the working principles of lymphocytes are not known, they are related in some way to spiritual values such as love, enthusiasm, and peace of mind. Likewise, it is known that the immune systems of people whose spirituality has been weakened by depression and stress are more susceptible to break down. Unless those people recover by activating their spiritual dynamics, like faith in destiny, they are under a greater threat of cancer. Yet, this world is a place of examination. We cannot claim that every cancer is due to a damaged spirituality; we should not forget that cancer might occur due to different reasons. 4. Eosinophils: These are a kind of leukocytes that can kill some sort of parasites. They cling to parasites and release the granules in their cytoplasm into the parasites. These granules contain enzymes which destroy parasites. 5. Mast cells and basophils: Mast cells and basophils play a central role in inflammatory and immediate allergic reactions. They are able to release potent inflammatory mediators. Mast cells function out of the veins and protect the tissues in the body, whereas basophils are similar cells found in the bloodstream. F – Factors in plasma: 1.Antibodies: These are secreted into the blood by plasma cells. They fight against the germs that have stimulated them. They show their impact directly (neutralizing bacterial poisons, gathering and precipitating bacteria, neutralizing viruses, pulling microorganisms into pieces) or by activating a very special system called a complement. 2.Complement proteins: When inactive complement proteins in plasma are stimulated by antigens and an opposing antibody complex, active complement compounds are brought to life. These compounds have various effects like chemotaxis, opsonization, development of inflammation as a result of stimulation of mast cells and basophils, and the destruction of microorganisms. The complement system can be stimulated by microorganisms without a need for antibody development (without a need for lymphocytes); this can be seen as a manifestation of our Creator”s name Mudabbir (managing, administering, controlling every being in balance and order). This ensures the stimulation of a complement system under conditions that lack antibody production. Hence, the body is never left completely undefended. Is it really possible that such an amazing defense system, that requires unlimited knowledge and power, and that consists of every kind of alternative action, can come into existence by itself? 3.Interferons: Viruses invade body cells and synthesize proteins that contribute to their proliferation. Interferons, secreted by lymphocytes or other leukocytes, are created so that they can attach themselves to virus-infected body cells and obstruct the production of those proteins. Hence, these viruses cannot proliferate. 4.Lysozyme: Mentioned in the earlier part concerning body secretions, lysozyme is also available in the blood and kills bacteria there. 5.Properdin: This is a kind of protein available in the plasma which can neutralize viruses and destroy some bacteria types. 6.Acute phase proteins: These are a large number of serum proteins (C-reactive protein, etc.) that are swiftly synthesized by the liver and that are employed in defense during infections. 7.Beta-lysin: A substance that destroys some types of bacteria. G – Events caused by infections: 1. Inflammation: Inflammation is a response that is designed to protect tissues against tissue destruction, caused by factors like infection, excessive heat, and trauma. When a tissue is invaded by microorganisms, it starts to be destroyed; certain matters come out of those tissue cells (as mast cells) and lead to certain reactions in that zone. a.Vasodilation: As the little veins transporting blood to a tissue widen, more blood rushes in and more neutrophils are carried to that zone. Meanwhile, a color enhancement (blushing) occurs in that place. b.Increase in permeability of the capillaries: Neutrophils can penetrate into the tissues more easily. Plenty of water also passes through tissues, so some edemas (swelling in tissues) develop. Finally, coagulation proteins in the plasma, which can rarely infiltrate from capillaries to the tissues because of their large molecular structures, pass to the tissues and clot the liquid here. Hence, lymph veins, which are responsible for returning the liquid to the blood circulation, are plugged by clots. Consequently, inflammation detains microorganisms in that specific zone and prevents them from spreading throughout the body. Microorganisms are also destroyed by tissue macrophages in the inflammation zone and the migrant neutrophils working there. (The more a bacterium causes tissue damage, the harder it passes to blood.) Then, remnants of dead bacteria, damaged tissue cells, and neutrophils that are also destroyed after the phagocytosing of between 5 and 20 bacteria soften the inflammation by dissolving and creating some pus in that zone. The pus streams out by itself or is relieved by an incision being cut in the covering skin. 2. Fever:Toxins coming out of some bacteria and some secretions of microbe-phagocytosing cells lead to an increase in body temperature. Fever stops reproduction of microorganisms and kills them by ruining their structures. Within this framework, the occurrence of fever is beneficial; it indicates that the body is resisting and struggling to kill the microbes. Therefore, fever should not be reduced as long as it is not too high to cause brain damage (especially for children). 3. Cough: A cough helps the body discharge the microbes in the respiratory paths. Thus, cough medicines should not be used immediately, except in cases of whooping cough. 4. Diarrhea: This helps the body rid itself of feces quickly, so medicines to stop diarrhea should not be used, either. However, in cases of cough and diarrhea, a person should know their own strength and the strength of their immune system well and take medication accordingly. When we consider all these defense mechanisms, this question occurs in our minds: Do we protect ourselves against infections or is there someone who operates various immunity mechanisms in our bodies and controls them at every moment with His infinite knowledge and power?