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Binge drinking may contribute to depressed immune system function

IOWA CITY, Iowa -- Immune system function is decreased in alcoholics and alcohol abusers with liver disease, making them more susceptible to infections and disease. Recent research done at the University of Iowa suggests that alcohol, rather than the liver disease, is largely responsible for the decrease in immune system function -- perhaps by decreasing the number of immune system cells. Sporadic alcohol intake, or binge drinking, may contribute to that cell loss, according to Dr. Robert Cook, professor of pathology at the UI College of Medicine and Iowa City Veterans Affairs Medical Center.

Some of those findings were published in two papers in the September issue of the journal Alcoholism: Clinical and Experimental Research, by Cook and UI colleagues.

The researchers looked specifically at the activity of one type of immune system cell, the natural killer cell. Natural killer cells are special because they recognize and attack cells infected with a virus the first time they "see" them. Most other immune system cells must be previously exposed to a foreign invader in order to attack the virus. Immediate recognition of virus-containing cells makes natural killer cells an important and early line of defense against viral illnesses such as human papillomavirus, cytomeglovirus and even HIV. They may also provide protection against some cancerous tumors, though this remains unproven in humans.

Natural killer cell activity is decreased in some alcohol abusers and alcoholics with liver disease. However, why is not clear and a source of controversy among scientists. When natural killer cells are studied in the laboratory in culture, some researchers find that the addition of alcohol decreases the natural killer cell's virus-fighting activity, but others find that cell activity is stimulated by alcohol.

Cook's work shows that normal natural killer cells in culture are stimulated by brief exposure to alcohol. He and his colleagues observed that natural killer cells bathed in alcohol increased their activity after the alcohol was removed, indicating that natural killer cell activity is in constant fluctuation during a situation like binge drinking.

Therefore, Cook hypothesizes that the decrease in natural killer cell activity seen in alcoholics and alcohol abusers with liver disease is most likely due to the presence of fewer natural killer cells at work rather than a decrease in cell activity.

Cook and his colleagues, Drs. Zuhair Ballas, Douglas LaBrecque, Brian Cook, Jack Stapleton and graduate student Feng Li, hope to determine exactly how excessive alcohol use causes immune system changes and increased rates of infectious disease.