Animal Immune Systems

THE GREAT SHIELD

"...He is our Help and our Shield."
Psalm 33:20

Protection comes in many forms. The lion raises his head, brandishing his formidable teeth; any would-be attacker scurries into the distance. A prick from the rose bush reminds us that Jesus has given this famous flower beauty as well as a means of defense. The mere sight or sound of a bee sends some people into a panic.

These are examples of how the Heavenly Father supplies instruments of protection for each creation. It is, in fact, rare to find a plant or animal lacking some obvious form of external defense. These conspicuous armaments are overshadowed, however, by the complexity of internal protection which Christ our Creator has built into every living thing. His construction of hidden defense systems, protecting creatures from unseen disease-causing microbes, clearly demonstrates the Lord's love. His concern is obvious; He protects life not only on the outside, but through and through. The Lord Jesus Christ is more than deserving of the title "The Great Shield."

The Lord Jesus has created several lines of defense or barriers against microscopic foreign invaders in almost all creatures. Throughout creation, germs are met with a myriad of defensive strategies that He has invented. The roots of plants secrete chemicals that act as antibiotics. This makes sense when we realize the incredible number of soil bacteria and fungi surrounding the underground parts of a plant.1 Similarly, animals produce a number of substances which have protective properties: the oils and sweat of skin; tears; mucous of the digestive tract; stomach juices; and saliva.

Would-be germs must also pass through formidable and well-constructed physical barriers. The skin of a horse or an elephant, the thick bark of a tree, or the tough exoskeleton2 of an insect or spider are all examples of protective clothing the Lord has woven.

Microscopic intruders able to penetrate these outer defense shields will then be met by an ever-present army of cells or circulating chemicals ready to destroy anything foreign. Most animals possess swarms of eating cells called phagocytes (FAG - o - sights). Vertebrates (fish, amphibians, reptiles, birds, and mammals) have two basic types of phagocytes: polys (PALL - lees) and macrophages (MACK - row - fa - juz). The phagocytes of invertebrates (animals without backbones) are called hemocytes. They are found in insects, spiders, oysters, earthworms, and lobsters, to name a few. Although different in size and shape, the phagocytes of all animals perform the same basic job—they're "eating machines." They devour anything that appears alien.

Germs able to run the gauntlet of phagocytes will next be challenged by trillions of circulating antibodies3, or, in the case of invertebrates, chemicals called lectins. Antibodies and lectins generally do one of two things: (1) they attach themselves to the foreign invader, "seasoning it," thus making it more appealing to the eating cells, or (2) they attack and destroy the germ on the spot.

People and mammals also possess strategically placed "forts" that prevent the spread of infection throughout the body. These forts, called lymph nodes, contain sophisticated cells which produce antibodies, help contain and destroy invaders, and coordinate the body's immune army. Although fish do not have lymph nodes, they do possess tissues similar to our tonsils, which are located in their gills.

God did not simply create these sophisticated defensive strategies and then leave life to its own devices. His concern for each creature becomes even more evident when different animals are studied. For instance, the Lord Jesus tenderly protects the baby zebra and young elephant by supplying them with disease-preventing antibodies in their mother's milk after birth. Without these antibodies the infant animals would die.4

When you think about it, it's hard to imagine why vultures don't succumb to disease, considering their diet of dead, rotting animals. Their role in cleaning up the effects of death is integral to a healthy world; this is one reason Y'Shua* gave them what seems to us a disgusting appetite. Although we may consider vultures grotesque, their bald heads and bare necks serve a purpose. Any germ that gets on the barren skin while they are eating is then exposed to the cleansing rays of the sun. In addition, the high acid content of their stomachs purifies the germ-laden meat they eat. Vultures also secrete antibiotic-like chemicals which keep their bodies healthy.

The Lord Jesus has given large animals and humans an advanced immune system, but He shows kindness toward even the lowliest creatures by the built-in protection He has given them as well. In the case of the diving beetle, for example, the Lord Jesus has provided unique protection. The diving beetle lives most of its life in water and as a result becomes coated with bacteria that reside in ponds. Using his built-in bathroom cleanser, the beetle rubs a special disinfectant from its hindquarter glands all over its body, killing the slimy coating of germs.5

The depth of the Creator's concern is also demonstrated in the caterpillar. When it changes into a butterfly the caterpillar's internal organs are completely dissolved, releasing a large number of intestinal bacteria. Its wonderfully and carefully designed immune system easily handles the onslaught of germs!6 This is a normal part of the life of a butterfly-to-be. If this happened to people, we would all develop severe infections (peritonitis) and die!

All creepy-crawlies are protected with the same degree of concern by our Heavenly Father and the magnitude of this protection is incredible. Consider this: there are an estimated 1,000,000,000,000,000,000 insects in the world; that is a million times a million times a million insects! Jesus protects and cares for each one, maintaining within each a complex immune system. Even the lowly earthworm is protected by defenses that are more sophisticated in their design than any of the weapons of the world's superpowers!

Christ does not limit His vigilance to animals. He has supplied vegetation with numerous weapons in germ warfare as well. Although plants do not produce antibodies, they are permeated by several antibiotic-like chemicals (phytoalexins). Y'Shua has impregnated the bark of trees with these antibiotics, reinforcing their first-line of defense. In addition, essential oils and tannins found in vegetation help plants resist infection from molds. The heartwood of some trees contain stilbenes which help to prevent destruction by decomposing bacteria. Several plants either contain or release cyanide, a poison deadly to microorganisms.

The Lord also gave plants a way to limit disease if an infection takes hold. When a fungus, for instance, tries to invade an immune plant it may succeed in killing some of the healthy plant cells. As the plant cells die, however, they release toxins which then kill the fungus. The fungal infection thus remains localized and the plant as a whole stays healthy. You may have occasionally noticed brown spots on the leaves of different plants—this may be evidence that the invasion by a hungry mold has been thwarted.

There is yet another way that the Lord Jesus Christ has protected all plants and animals from infectious diseases. He created each creature on earth with a very precise architectural or chemical make-up. Like all organisms, germs need specific nutrients in order to grow and multiply. While an invading microbe may be able to find these essential nutrients in one particular species of plant or animal, they may very well be lacking in another. Even within groups of people some individuals may get sick with strep throat, for example, while others won't.

Christ's unimaginable ability to create incredible variety in the chemical architecture of living things prevents the easy transfer of an infection from one plant, animal or person to another. Here are some other examples:

• people, pigs and horses can get the flu, but rabbits cannot
• cats don't catch measles
• cattle can die from anthrax infection, pigs get a sore throat, but dogs are immune
• reptiles and fish don't get rabies
• leprosy occurs in man, but not in animals.

Unfortunately, there are several things that have a negative effect on immunity. The most notable is age. As a plant, animal, or person gets older, the ability to fight off infection steadily declines. The apostle Paul bluntly summarized this problem with his observation that "outwardly we are wasting away" (2 Corinth. 4:16).

Research has shown that stress, disease, hormones, and diet also affect life's defense capabilities. Poor nutrition, or the opposite—overeating and obesity, decreases the efficiency of the immune system. Extremes in temperature also affect immunity. Fish are more prone to infectious diseases during fall and winter,7 and the antibiotic activity in pine trees is much greater in summer than in autumn.8

Christ seems to counter these negative effects by supplying additional protection using the very organisms that can cause disease. Did you know that some of the most important antibiotic medications used in human and veterinary medicine come from microbes that live in the soil? In fact, the familiar smell of soil is produced by a group of mold-like soil creatures which manufacture antibiotics.

Christ's great concern for His creation is again reflected in the marvelous ways He protects all living things. God did not originally desire for creation to be challenged and frustrated. In the Lord's great foresight, however, He engineered defensive systems that can handle most infectious assaults in plants, animals, and people. Although He has provided breakthroughs in medicine to improve our health, the vast majority of protection was set in place a long time ago. The Heavenly Father has used creation to abundantly demonstrate that He is The Great Shield.

* Hebrew for Jesus

Notes

1 L.V. Metlitskii and O. L. Ozeretskovskaga, Plant Immunity—Biochemical
Aspects of Plant Resistance, (New York: Plenum Press, 1968), pp. 7-8.
2 Mammals, birds, reptiles, amphibians, and most fish have skeletons
made of bone found on the inside of the animal. Insects and spiders,
however, have their skeletons on the outside of their body. Similar to a
suit of armor worn by a knight, the exoskeleton helps protect the insect
and spider from harm and provides a framework within which to live
and move.
3 Antibodies are protein molecules produced by special cells (called plasma
cells) in people and many animals. Antibiotics are a wide variety of
chemicals which affect the growth or reproduction of microbes and are
found primarily in plants.
4 Nilsson, Lennart, The Body Victorious, (New York: Delacorte Press,
1987), p. 35.
5 Dorothy Hinshaw Patent and Paul C. Schroeder, Beetles and How They
Live, (New York: Holiday House, 1978), p. 105.
6 Brehélin, Michel, Ed., Immunity in Invertebrates, (Berlin: Springer-
Verlag, 1986), p. 71.
7 Cooper, Edwin L., Langlet, Calude, and Bierne, Jacques, Eds.,
Developmental and Comparative Immunology, (New York: Alan R. Liss,
Inc., 1987), p. 44.
8 L.V. Metlitskii and O. L. Ozeretskovskaga, Plant Immunity—Biochemical
Aspects of Plant Resistance, (New York: Plenum Press, 1968), p. 19.