In the study led by a researcher at Loyola University Chicago Stritch School of Medicine, participants drank alcohol depending on their weight.
Twenty minutes after reaching peak intoxication, their immune systems revved up. But when measured again, at two hours and five hours after peak intoxication, their immune systems had become less active than when sober, researchers said.
The study included eight women and seven men with a median age of 27.
Each volunteer drank enough shots of vodka - generally four or five - to meet the definition of binge drinking.
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The blood samples showed that 20 minutes after peak intoxication, there was increased immune system activity. There were higher levels of three types of white blood cells that are key components of the immune system: leukocytes, monocytes and natural killer cells.
There also were increased levels of proteins called cytokines that signal the immune system to ramp up.
The study will be published in the journal Alcohol.