For individuals with long-term drinking problems, lung infections tend to be the worst outcome compared to those without a history of alcohol abuse. It’s an association observed by physicians for centuries, but it was not until recently that researchers were able to explain exactly why this is so. A recent study has solved the puzzle, finding that alcohol is actually able to impair cells necessary for our immune response against the flu virus.

Disabled The Mice's Immune Response 

In an effort to discover the effects of alcohol on the human immune system, researchers from the University of Iowa mixed alcohol into the drinking water of mice for a period between eight and 12 weeks. It was not long after that the researchers were able to see that alcohol specifically targeted the mice’s immune response against the influenza virus, rendering them more susceptible to both becoming infected with the virus and displaying more severe symptoms upon infection.

In order to understand how exactly alcohol impairs an immune system, it’s important to first know functions of the immune response. Dr. Kevin Legge, lead author of the study, explained in a press release how an unadulterated immune system offers us protection from the common influenza virus. In the our complex immune systems, there are actually just two components responsible for fending off the flu virus.

These consist of “antibodies which neutralize the virus, preventing infections, and T-cells, which find and kill infected cells,” Legge explained. In his study, Legge found that alcohol can inflict physical and, ultimately, detrimental changes to these CD8 T-cells. “Chronic alcohol attacks the CD8 T-cell immune response on two separate levels: limiting the number of cells that can fight the infection, and limiting the ability of the remaining cells to fight," Legge wrote. However, in laymen’s terms, Legge’s study found that years of chronic alcohol abuse renders an immune system unable to adequately fight off the dangerous flu virus.

What This Study Means For Us

The effects on the mice reflect what occurs in human bodies, but as Legge told Medical Daily in an email, translating the dose of alcohol given to the mice into an actual human drinking pattern is more complex. “What we study is chronic alcohol consumption and the model was set up to model and reproduce those effects that have been observed in humans that have been drinking for extended times (decades, etc),” Legge wrote. However, he did speculate that similar results found in this study may be able to be seen in an individual who habitually maintained a blood alcohol level between 0.4 BAC and 0.04 BAC over a period of six to 10 years.

Dr. Illhem Messaoudi, a commenter on the research article and researcher who also studies alcohol's effect on the immune system, explained to Medical Daily in an email just how extensive this harm can be. Messaoudi highlighted that alcoholics are up to seven times more susceptible to lung infections than the rest of the population, and these lung infections lead to not only poor health but also economic strain. However, if you or your loved one suffers from alcohol abuse problems, please don’t be disheartened by the study’s results.

Researchers hope that the findings will go on to help the development of new drugs that may help alleviate this problem. “The data from this study can be used to improve vaccination of at risk populations to mitigate the increased incidence of pneumonia and the costs associated with that,” explained Messaoudi in her email. “Developing an intervention to improve immunity in these subjects could in theory repair permanent damage that lasts after drinking cessation and can lower health costs.”

Source: Legge KL,  Hemann EA, McGill JL. Chronic Ethanol Exposure Selectively Inhibits the Influenza-Specific CD8 T Cell Response During Influenza A Virus Infection. Alcoholism. 2014