April 9, 2019 | Henry Richter

Wonders of the Immune System

Note: While the editor is out of town, we are bringing you readings of interest from creation books associated with CEH.

Wonders of the Immune System, by Dr Henry Richter

from Spacecraft Earth, a Guide for Passengers (CMI, 2017, ch. 2, “The Spacesuit: The Amazing Human Body,” pp. 49-51).

The adaptive immune system is found only in vertebrates. This complicated system has multiple components, which include antigens, antibodies, and various types of blood cells such as B and T lymphocytes. The collective interaction of these components results in a coordinated, multi-level response to infectious organisms. Antigens are things that trigger an immune response. They might be proteins, polysaccharides (complex carbohydrates), or foreign substances, including molecules found in bacteria, viruses and fungi, or substances that mark the surface of cells with foreign materials such as pollen or transplanted tissue.

When antigens are detected, the body goes to work producing custom antibodies to fight them. Antibodies, or immunoglobulins, are proteins directed against specific antigens; they are formed in the lymph nodes or bone marrow by mature D lymphocytes called plasma cells. These are placed into circulation throughout the body to bind and neutralize antigens wherever they are found. This type of response, called humoral immunity, is mainly against toxins and free pathogens (those not ingested by phagocytes) in body fluids.

A second type of response, called cell-mediated immunity, does not produce antibodies, but instead triggers the production of T lymphocytes, which act against specific threats. T cells are able to neutralize bacteria, fungi, cancer cells, transplanted tissue cells, and cells that have been invaded by viruses. In each case, the immune response prevents the invaders from causing further damage to the host. As if that were not enough, there’s another immune response called the complement system. This is composed of a group of proteins circulating in the blood. They facilitate the immune response in two ways: by attracting phagocytes (‘eating cells’) to the area so that they can swallow the invaders, and by forming a protein complex that attaches to the foreign cell, causing lysis (splitting, or death) of the invaders.

Two remarkable qualities of our immune system are its specificity and memory. When an antigen enters a body, it elicits production of either a specific antibody or specific immunologically competent cells; that is, the antibody or the cells will neutralize only the antigen that evokes them. Furthermore, the system exhibits what appears to be memory. Once challenged by an antigen such as the measles virus, the body ‘remembers’ it for years and usually for life. The child who has had an attack of measles becomes permanently immune to it. If the child is exposed to this specific antigen at a later date, the immune system recognizes it and responds, and thereby prevents a reinfection. Indeed, these two characteristics of the immune system—specificity and memory—serve as the basis for preventive immunizations. Inoculation of infants or children with an inactivated or attenuated biotic agent will cause the immune system to be made alert to such an antigen, should it appear at a later date. Poliomyelitis, for example, once dreaded as a leading cause of paralysis and death, has been effectively controlled, if not abolished, with the polio vaccine, at least in most developed countries.

Medical science and physiological research has barely begun to understand all of the facets of the human immune system. We surely could not survive without it. Of the body systems we’ve examined so far, it’s a great example of multiple, disparate parts working together in harmony. It could not have arrived piecemeal. A phagocyte that can ‘eat’ another cell would be a monster if not responsive to a signal transduction system that tells it what to attack. A thymus gland that can match antibodies to antigens would be useless if other parts of the system did not recognize the antibodies in order to attach to infected cells and destroy them. The lymph nodes, the marrow within our bones that produce blood cells, the specific enzymes that circulate in blood and lymph, and a host of other things are all involved together, each one necessary to make the immune system work. Thankfully, everything is there that is necessary, and the system usually works very well.

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