Lab experiments show that cells that line the mouth become more susceptible to infection with HIV when they’re exposed to alcohol.

The finding suggests that drinking alcohol may facilitate HIV infection by oral sex, say Dr. Jun-ying Zheng of the UCLA Dental Institute and colleagues.

While alcohol consumption has been linked to HIV infection, the researchers note, most studies have focused on its effect on risky sexual behavior rather than any direct effect on the mechanism of infection.

To investigate, they exposed cells from the lining or epithelium of the mouth obtained from HIV-negative individuals to various concentrations of alcohol, and then to a strain of HIV modified with green fluorescent protein in order to make the detection of infection easier.

Oral epithelial cells exposed to 4% ethanol for 10 minutes showed three- to six-fold greater susceptibility to infection with HIV strain, Zheng’s team reports in the Journal of Acquired Immune Deficiency Syndromes.

They note that the ethanol concentrations they tested are similar to the alcohol content of beer, “the most widely consumed alcoholic beverage of Americans.”

SOURCE: Journal of Acquired Immune Deficiency Syndromes, December 1, 2004.