How Does Stress Affect The Immune System

How does stress affect the immune system

The immune system is designed to defend the body against millions of antigens that would otherwise invade it. None of these things are able to get in when your immune system is working efficiently, but the moment your immune system stops functioning properly, the opportunity for antigens to attack is available.
Kiecolt-Glaser (1984) carried out a natural experiment investigating whether the stress of short-term stressors had an effect on immune system functioning in medical students. Blood samples were taken one month before and during exam period itself. Immune system functioning was assessed by measuring NK cell activity in the blood samples. Participants also completed a questionnaire to measure other life stressors they were experiencing.
They found that NK cell activity was significantly reduced in the second blood sample compared to the sample taken one month before. This suggests that short-term stressors reduce immune system functioning thus increasing vulnerability to illness. Kiecolt-Glaser also found that the highest level of loneliness had the lowest NK cell activity.
Exam-related immune changes have also shown to have a dramatic effect on the rate at which wounds heal. Marucha (1998) inflicted a ‘punch biopsy’ in the mouth of the
students either during the summer holidays or three days before an exam. The wounds given before the exam took 40% longer to heal than the wounds during the holidays.
Examinations represent a relatively short-term stressor, so we might expect to find an even greater effect on the immune system functioning under conditions of chronic stress.
Marital relationships can be stressful, as can separation from a marital partner. Kiecolt-Glaser (2005) tested the impact of interpersonal conflict on wound healing. She found that blister wounds on the arms of married couples healed more slowly after they had a discussions which were conflicting rather than supportive. Kiecolt-Glaser (1987) compared women separated from their partners with matched married controls. They found poorer immune system functioning in women who had separated during the last
year.

To evaluate, Lazarus (1992) suggests that there are various reasons why a relationship between stress and illness is difficult to establish. One is that health is affected by many different factors. As a result, there may be little variance left that can be accounted for by stress. Another reason is that health is generally fairly stable and slow to change. As a result, it makes it difficult to demonstrate that exposure to particular stressors have caused a change in health. The last reason is that to demonstrate how stress affects long-term health would involve continuous measurement over time. This would be expensive and impractical, therefore most research has concentrated on relatively short periods of time.
There is also a theory that stress can sometimes enhance the immune system. Research has supported the observation that short-term stress does not always decrease immune system functioning, but can also enhance it in some circumstances. Evans (1994) looked at the activity of an antibody-slgA-which helps protect against infection. Evans arranged for students to give talks to other students. These students showed levels of increased slgA, whereas levels of slgA decreased during examination periods stretched over several weeks. Evans (1997) proposed that stress may have two effects on the immune system: up-regulation for short-term acute stress and down-regulation for chronic stress.
Research has shown consistent gender and age differences in the stress/immune system relationship. Women show more adverse hormonal and immunological changes in the way they react to marital conflict (Kiecolt-Glaser, 2005). As people age, stress has a greater effect on the immune system functioning, making it harder for the body to regulate itself (Segerstrom and Miller, 2004).