The Immune System / The Thymus Gland

Anatomy and Physiology

The thymus gland is a pink-grey organ that lies underneath the top of the breast bone. In animals it is known as the sweetbreads.

No one knew much about the thymus until recently. On autopsies it was noticed that young adults that had died in traumatic accidents often had much larger thymus glands than those dying from diseases of a chronic nature, and it was also believed that the thymus ceased to function after childhood.

We are just now unraveling the mysteries of this gland. The thymus processes a type of white blood cell known as a T-lymphocyte. These T-lymphocytes govern cellular immunity which means they help cells recognize and destroy invading bacteria, virus, etc., abnormal cell growth such as cancer, and foreign tissue.

Experiments done on animals have shown that if the thymus is removed before birth the baby will accept an organ transplant without rejecting it (it has lost its ability to recognize foreign tissue). At the same time that baby will exhibit little or no ability to fight off disease. Also animals that had their thymus removed would develop cancer rapidly upon injection of cancer cells into their body, while animals with an intact thymus would in most cases destroy the cells.

A Historical Look at The Thymus Gland

"'Has it yet fallen to the lot of any writer upon the thymus to write the truth and be believed?---Beard, 1902.'" (Diamond, M.D., page 8)

"A recent case described in a medical journal is that of a young boy who was admitted to the hospital in coma from a severe viral pneumonia. He was unconscious, with a high temperature, and was on forced respiration, being unable to breathe unassisted. Everything was done to resuscitate him, but it was quite obvious that he was going to die. The equivalent of a T-cell count was performed; approximately one fifth the normal level was found. He was then given an injection of thymus extract, and within twenty-four hours the entire process had reversed itself. His temperature was down, he was breathing unassisted, and he was conscious. This is the kind of dramatic recovery we are going to see more and more as accurate testing of thymus function and administration of thymus extract, when indicated, becomes routine in medical practice, as I am sure it will in the next five or ten years. As one of the most eminent workers in the field has said, 'The second golden age of 'thymology' is just beginning.'*" (Diamond, pages 10-11)(*J.F.A.P. Miller, Lancet. December 16, 1967, p. 1302.)

"In spite of modern research findings, the myth of the shriveling, useless thymus dies hard. Whenever I lecture on the thymus gland to medical audiences, I am reminded that 'everyone knows that the thymus gland has no function in adult life.' But the evidence accumulated over the last twenty years on the thymus gland's role in immunology is so overwhelming that it is hard for me to believe that there is not some unconscious factor working to deny it the recognition due to it." (Diamond, M.D., page 9)

"The thymus gland lies just beneath the upper part of the breastbone in the middle of the chest. It is present in all mammals, and is called the sweetbread in calves. until the 1950s little was understood about the thymus, although there had been clues to its function for many years. As far back as 1902, Foulerton, a London physician, was using thymus extract in the treatment of cancer. However, the standard teaching was that the thymus gland had no function at all in the adult, a delusion fostered by the fact that during autopsy the thymus was usually found to be quite small and atrophied. This is because the thymus gland, in response to acute stress such as an infection, can shrivel to half its size in twenty-four hours. No wonder it was in a state of atrophy when examined post-mortem!" (Diamond, M.D., page 8)

"The fact that the size of the thymus was generalized from autopsy observations led to a tragic misdiagnosis of illness in children in the 1920s to the 1940s. It was known from routine autopsies that children have larger thymuses than adults. however, when children who died suddenly, as in 'crib death,' were found at post-mortem examination to have particularly large thymus glands, they were thought to have died from a thymus-related disease, a disease given the name 'status thymicolymphaticus.' Research on the thymus gland in the 1950s, along with further evidence from post-mortem examination, brought this disease into question. Pathologists took note of the fact that battlefield autopsies thymus glands than men of the same age who died from chronic illness in a hospital. Eventually it was realized that the thymus shrinks rapidly during serious illness or great physical stress. The children gland had time to shrink; their large thymuses were actually the normal size. A whole disease had been constructed on the erroneous idea that the thymus gland had swollen and caused death. To think that children's thymus glands had frequently been irradiated to make them smaller on the assumption that this would reduce the chance of illness! What it did was destroy a vital part of their immune system and make them susceptible to infections, cancer, and chronic diseases!" (Diamond, M.D., pages 8-9)

The Thymus Gland - Origin of its Name

"At one point in the Iliad, Achilles says: 'Waking like smoke in the breasts of men, even as Agamemnon angered me, but we will let bygones be bygones, quieting the thymos in our breasts.' Thus, thymos was metaphorically a rising of smoke in the breast, as its Indo-European roots imply." (Diamond, M.D., page 129)

"Although thymus comes from the Greek word thymos, its roots go deeper. Tracing it back beyond the world of Socrates and Plato, we find that thymos is from the Indo-European root dheu, which is the base of a wide variety of derivatives meaning 'to rise into flames,' 'to rise in a cloud,' 'to smoke.' In Sanskrit the word was dhuma, from which come 'fume' and 'perfume'." (Diamond, M.D., page 128)

"Interestingly enough, the word thymus is derived from the Greek thymos...which is untranslatable into modern terms but denoted life force, soul, and feeling or sensibility. As Onians points out, thymos originally referred to the breath. It was the stuff of consciousness, the spirit, the breath-soul, upon which depended a man's energy and courage. Even the earliest origins of the word implied rising into flames, as a cloud, spirit, which relate it to the concept of soul and Life Energy." (Diamond, M.D., page 29)

"L., from G, thymos, thyme: so called because shaped like the thyme flower." (Webster's Dictionary, page 1,906)

"...thyme derives its Latin name from the plant's serpentlike growth. Pliny recommends it as an antidote for snakebites..." (Ody, page 104)

"In the second century, Galen gave the name thymus to the pinkish-gray two-lobed organ in the chest because, it is said, it reminded him of a bunch of thyme." (Diamond, M.D., page 129)

"But the thyme plant itself was so named because it was burned as incense to the gods. Indeed, the altarlike elevation in the center of the orchestra of a Greek theater was called the thymele, and sacrificial incense was placed in the thymiaterion, or censer. Thymos, then, was a rising of smoke, a burning of incense, a sacrificing up to the gods--all taking place in the chest, the inner altar. It was aspiration, songs of praise, spirit, and the putting out of love. It was the breath-soul, on which depended a man's energy and courage." (Diamond, M.D., page 129)

"...the thymus...this vital organ." (Weston, M.D., page 99)

"the thymus of an animal, when used as food, is called sweetbread..." (Webster's Dictionary, page 1,906)

"The thymus gland...is present in all mammals, and is called the sweetbread in calves." (Diamond, M.D., page 8)

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