How Stress Affects Your Immune System

By Dr. Linda Kennedy

Stress is one of the leading health problems in Western society. It is characterised as an emotional or physical strain on the body, caused by physical, psychological or chemical stressors. Stress may be acute, caused by things such as work pressures, surgery, experiencing a fright or increased physical exertion, whereas chronic stress occurs over weeks or years and may be due to stressors such as sleep deprivation, social isolation or role strain.

The immune system is comprised of biological structures and processes by which the human body identifies and kills antigens in an attempt to protect the body from harm and disease. It is a well-regulated and adaptive system. The first line of defence includes a physical barrier such as the skin, and the innate response, inflammation. The cell-mediated immune response is part of the adaptive immune system and uses sensitised T-cells to recognise antigens and attach to them in an effort to inactivate them. Helper T-cells, or CD4 cells are activated by interleukin-1 and work to produce interleukin-2 and interferon, which stimulate the production of antibodies. Suppressor T-cells work to maintain immune system homeostasis by suppressing immune system activation, while cytotoxic T-cells destroy the antigen they are specific for.

When an individual encounters a stressor, a number of mechanisms in the body are activated in response. These mechanisms also interact with the immune system, although the exact way in which this occurs is not completely understood. The autonomic nervous system directly innervates immune system tissues through influencing the receptors for neurotransmitters on the surface of immune cells. Activation of the hypothalamic-pituitary-adrenocortical axis leads to the production of corticotropin (ACTH), endorphins and glucocorticoids.

Cortisol is primarily immunosuppressive, resulting in a reduction in the number and function of leucocytes and changes in natural killer cell activity. Glucocorticoids and epinephrine also act to suppress the immune response while in contrast norepinephrine has been shown to enhance immune cell readiness during infection. The sympathetic adrenomedullary system is also activated when the body comes under stress, releasing catecholamines and enkephalins, both of which have an effect on immune system function. The most common catecholamines are epinephrine, norepinephrine and dopamine.

While stress clearly has an effect on the immune system, it is a complex interaction. Not every individual reacts to the same extent, and not every individual reacts the same way and research findings can sometimes be paradoxical. It is believed, however that there are commonly two groups of people, high reactors and low reactors, with high reactors more likely to have a significant physical response to stressors. This response includes significant increases in blood pressure, heart rate and catecholamines, as well as an increase in circulating CD8 lymphocytes. In addition, T-cell response to mitogenic stimulation during periods of stress is reduced, although this is attributed to the expanded suppressor/cytotoxic T-cell population. The increase of epinephrine in the body results in an increased percentage of natural killer cells, and decreased amounts of CD4 cells. Together these changes result in a lowered immune system, leaving the body open to infection.

Psychological stress has been specifically linked to increased susceptibility to, and duration of viral infections. Latent viruses are more likely to surface, as the body’s defences are lowered. Stressors such as medical examinations or experiencing marital issues can reactivate viruses such as Epstein-Barr, and herpes simplex.

Research has also shown that infection rates rose from 27% to 47% in stressed individuals exposed to the common cold, and that infection was dose-dependent, with higher levels of stress associated with increased susceptibility to colds.

Likewise, HIV-positive males that were experiencing the stressor of concealing their sexuality have been shown to experience a more rapid progression into AIDS. Psychological stress is also associated with an impaired immune response in relation to several vaccinations including hepatitis B virus, rubella virus and the influenza virus. Individuals with a decreased immune response to the influenza virus have also been shown to experience higher rates of clinical illness for longer periods of time. Other health issues attributed to stress include ulcers, myocardial infarction, diabetes mellitus and delayed wound healing.

Unfortunately for some, the experience of stress is ongoing and unavoidable. If this describes you there are measures you can take to help keep your immune system boosted such as concentrating your diet on one that is rich in whole foods. Certain dietary supplements formulated from natural whole food sources can prove helpful and include Aloe vera, glyconutrients supplements and medicinal mushrooms which all have a positive impact on immune system function.

About the author: Dr. Kennedy has a solid education background sporting degrees in both organic chemistry and cellular biology. She has a graduate degree in Neuro Rehab Science and a PhD in nutrition. She currently owns a state of the art nutritional laboratory where she produces targeted and non-synthetic supplements for both her patients and clients.

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