Cocaine and Intensity of HIV Are Related in a Study of Mice

Research in mice may help explain something that doctors have noticed in people who are HIV-positive: cocaine use seems to make the disease progress faster and lead to more of the opportunistic infections that are the hallmark of AIDS. The reason is not known. Drug abusers often eat poorly, have unprotected sex and neglect their health in other ways, so it has been impossible to tell whether their problems are due to cocaine itself or to the other habits that often go with addiction.

A new study to be published in the March issue of the Journal of Infectious Diseases (2002; 185:701-705) suggests that cocaine is to blame. In the study by researchers at the AIDS Institute at the University of California at Los Angeles, specially bred mice were inoculated with human cells and HIV. Then the mice were given injections of either cocaine or a salt water placebo. Cocaine greatly enhanced replication of the virus and increased the number of human cells it infected and killed.

"We're talking about a 200-fold increase in viral load in these animals," said Dr. Gayle C. Baldwin, who directed the study. In addition, Baldwin said, the mice given cocaine had only one-ninth as many of the CD4 cells that help activate other parts of the immune system as the mice given salt water. When HIV wipes out the CD4 cells, the ability to fight off infections is lost. "We're seeing that the population of cells that are not killed off are churning out incredible amounts of virus," Baldwin said. But why that occurs is not known.

"I think [the research] has very significant implications for people infected by HIV," said Dr. Warner C. Greene, director of the Gladstone Institute of Virology and Immunology at the University of California at San Francisco. "One clearly sees that cocaine is doing something to the infection process," said Greene, who was not involved in the study.

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