Released May 26, 2008

AMARILLO, Texas – Relax. It may be an important part of helping the immune system defend against infectious organisms and other invaders, said a Texas AgriLife Extension Service specialist.

“The top recommendation for keeping a strong immune system is reducing stress,” said Andrew Crocker, AgriLife Extension gerontology specialist in Amarillo.

“Stress and what happens in your body during stress may negatively impact your ability to remain healthy,” Crocker said. “The good news is that lowering your stress can help your body maintain both your physical and your emotional health.”

The immune system is the body's defense against infectious organisms and other invaders, he said. When problems occur with the network of cells, tissues and organs that work together to protect the body, the result can be illness and infection.

Humans have three types of immunity:

– Innate immunity, which is a general protection everyone is born with and includes the external barriers of the body, like the skin and mucous membranes, which are the first line of defense in preventing diseases.

– Adaptive immunity, which involves the lymphocytes and develops over time with exposure to diseases or through vaccination.

– Passive immunity, which is "borrowed" from another source and lasts for a short time, such as antibodies in a mother's breast milk provide temporary immunity to diseases to which the mother has been exposed.

The cells that are part of this defense system are white blood cells, or leukocytes, Crocker explained. They come in two basic types which combine to seek out and destroy the organisms or substances that cause disease. Leukocytes are produced and stored in locations throughout the body, including the thymus gland, spleen and bone marrow.

The leukocytes circulate through the body between the organs and nodes by means of the lymphatic vessels and blood vessels, he said. In this way, the immune system works to monitor the body for germs or substances that might cause problems.

The two basic types of leukocytes are: phagocytes, which eat invading organisms; and lymphocytes, which allow the body to remember previous invaders and destroy them. The most common phagocyte is the neutrophil, which primarily fights bacteria.

“If your health provider is worried about a bacterial infection, she or he might order a blood test to see if you have an increased number of neutrophils triggered by the infection,” Crocker said.

There are two kinds of lymphocytes: B cells and T cells, he explained. Antigens, or foreign substances that invade the body, trigger the B cells to produce antibodies, which are specialized proteins that lock onto specific antigens.

“Antibodies and antigens fit together like a key and a lock,” Crocker said. “Once the B cells have produced antibodies, these antibodies stay in your body so that if the same antigen is presented again, the antibodies are already there to do their job.

“This is why if someone gets sick with a certain disease, that person typically does not get sick from it again,” he said. “This is also why we use immunizations to prevent getting certain diseases.”

Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it without help, Crocker said. That is where the T cells come in. The T cells are part of the system that destroys antigens that have been tagged by antibodies.

The Centers for Disease Control and Prevention recommends vaccines against pneumonia and the flu for older adults, in addition to routine boosters, like having a tetanus update every 10 years.

For more information on vaccines, talk to a health provider or visit http://www.cdc.gov/vaccines .

“Too, because your body may be constantly battling poor health habits, there are some other considerations, besides vaccinations, that may help keep your immune system strong,” Crocker said.

In addition to reducing stress and taking vaccines, other factors that may help improve the immune system are:

– Sleep. Prolonged sleep deprivation wears down immune protection but getting adequate rest can help boost defenses. Get seven to eight hours of sleep a night.

– Exercise. Moderate exercise, like a brisk 30-minute walk, most days each week, has been shown to increase immunity to disease. However, exercising too much may actually run down the immune system and make a person more susceptible to illness.

– Diet. Vary your diet with lean meats, fish, fruits and vegetables. This may be beneficial to the immune system as well as overall health.

For more information, visit the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, at http://www.niaid.nih.gov .

-30-

http://agnews.tamu.edu/showstory.php?id=498

Contacts: Andrew Crocker, (806) 677-5600, abcrocker@ag.tamu.edu

Kay Ledbetter, (806) 677-5600, SKledbetter@ag.tamu.edu