People who use cocaine may be more vulnerable to HIV, a new study suggests. Cocaine may inactivate immune cells called CD4 T-cells, which normally fight off HIV, according to CBS News. The drug also increases the proliferation of HIV through the cells.

“We ultimately hope that our studies will provide a better understanding of how drugs of abuse impact how our body defends itself against disease,” senior author Dimitrios N. Vatakis of the UCLA AIDS Institute said in a news release. “Such discovery can significantly improve the quality of life of drug users.”

Vatakis took a group of inactive CD4 T-cells from the blood of healthy adults and exposed them to cocaine. They then infected the cells with HIV. They took another group of CD4 T-cells and exposed them to HIV, but not to cocaine. The researchers studied the progression of HIV’s life cycle in both groups, and found after three days, cocaine made T-cells more susceptible to HIV.

The findings are published in the Journal of Leukocyte Biology.