Hormones and Your Immune System

Hormones and Your Immune System

Enemies of many kinds and in great numbers assault your body during your lifetime. We live our lives in a virtual sea of bacteria and viruses and we would surely drown without our immune system. The health of our immune system is affected by many factors, external, as we saw last issue, and internal such as our hormone system. Recent studies are only now showing us how complicated the relationship is between our immune system and hormone system.

A good example is a recent study showing that we respond to infection with complex bidirectional communication between our immune system and our neuroendocrine system.( 1) Cells of the immune system contain receptors for neuroendocrine hormones, that is, they receive messages. Your immune system then sends out the troops. It also forms amino acid chains called peptides. These peptides are similar to the hormones produced by your neuroendocrine system. They appear to function as immune regulators as well as information carriers from the immune system back to the neuroendocrine system.

Another recent study showed the importance of this communication. This study investigated the role of the pineal gland and its principal hormone, melatonin on the immune system, through its control of the release of cytokines (part of your immune system).( 2) The study was carried out on 31 cancer patients with advanced solid tumors who had failed to respond to chemotherapy and radiotherapy. The patients received melatonin for three months. Thirty-nine percent of patients achieved disease stabilization with no further growth of either the primary or secondary tumors. The researchers concluded that the pineal gland, and melatonin in particular, modulate immune function in cancer patients by activating the cytokine system which then exerts growth-inhibitory properties over a wide range of tumor cell types.

As we age there is a decline in function of growth hormone, especially insulin-like growth factor I (IGF-I) and immune system function. Dr. Khorram and colleagues showed the inter-relationship between these in a recent study.( 3) The study showed that administration of growth hormone releasing hormone significantly increased activation of the immune system. This in turn increased the IGF-1 levels and overall growth hormone levels.

An earlier study by the same researchers demonstrated a stimulator effect of dehydroepiandrosterone (DHEA) on immune function.( 4) Aging is associated with a decline in immune function and in DHEA production. DHEA administration resulted in a significant increase in activity of immune function.

In women the immune system is especially affected by hormone levels and is a good example of the important role that hormones play in immunity. A woman's immune system fluctuates over her monthly cycle. In order to successfully grow a fetus, and then nurture the helpless infant, and protect herself and that infant from disease, a women's immune system has to be very strong.( 5)

The key to female immune strength is the family of hormones known as estrogens. But a woman's immunity varies directly with her estrogen levels. The higher her estrogen levels, the stronger her immune response. Prior to ovulation every month, estrogen rises to strengthen immunity, increasing her store of lymphocytes so she can resist bacteria and viruses.

The high estrogen before ovulation primes the immune system for essential house-cleaning of the uterus and reproductive tract, to protect the descending egg from stray viruses and bacteria, and to clean the womb of debris in preparation for fertilization and implantation.

But at ovulation, estrogen levels drop sharply. Progesterone also increases to depress immunity. Otherwise the immune system would kill incoming sperm. Even if one sperm did survive, an estrogen-spiked immune system would kill and expel the fertilized egg as a foreign body. To prevent the immune system killing the fetus, estrogen levels remain suppressed, and progesterone levels remain high, throughout pregnancy.

Then, at birth, estrogen levels rebound and progesterone drops dramatically in most women. Immunity rises to its highest level. This miracle of design occurs so that the mother can resist infection at a critical time of nurture, and can also pass strong immune factors to the immune-weak newborn through her milk.

So, maintaining a healthy immune system means you have to maintain a healthy hormone system. For more details on how to do this, read Dr. Colgan's book, Hormonal Health.

(1.) Weigent DA, Blalock JE. Associations between the neuroendocrine and immune systems. J Leukoc Biol, 1995;58:137-50.

(2.) Neri B, et al. Melatonin as biological response modifier in cancer patients. Anticancer Res, 1998; 18: 1329-1332.

(3.) Khorram O, Yeung M, Vu L, Yen SS. Effects of [norleucine27] growth hormone-releasing hormone (GHRH) (1-29)-NH2 administration on the immune system of aging men and women. J Clin Endocrinol Metab, 1997;82:3590-3596.

(4.) Khorram O, Vu L, Yen SS. Activation of immune function by dehydroepiandrosterone (DHEA) in age-advanced men. J Gerontol A Biol Sci Med Sci, 1997;52:M 1-7.

(5.) Colgan M. Hormonal Health. Vancouver: Apple Publishing, 1996.

Colgan Chronicles.

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