By E. J. Mundell

Reuters 14 Feb. 2002

New York -- Experts have long known that cocaine abuse encourages risky behaviors linked to infection with HIV. Now, research in mice suggests the drug may also speed the cell-to-cell spread of the virus by up to 200-times.

"This is important, because cocaine use--specifically crack cocaine--is a significant public health problem, and it's particularly significant in populations at risk for contracting HIV," said researcher Dr. Gayle Baldwin, of the University of California, Los Angeles. Her team published their findings in the March issue of the Journal of Infectious Diseases.

Previous population-based studies have suggested that HIV-related disease progresses faster in drug abusers than in non-users. However, ethical and practical concerns have meant that its nearly impossible to carry out studies that would measure the effects of cocaine on HIV spread at the cellular level.

In their research, Baldwin's team developed a mouse model of human HIV infection. They first transplanted human cells into mice, then infected those cells with HIV. Next, they fed some of the mice cocaine in liquid form, at dosages roughly comparable to those used by human addicts. The rest of the mice received no cocaine.

"What we found was that cocaine use dramatically accelerated the spread of HIV infection," Baldwin told Reuters Health. In fact, the blood cells of mice fed cocaine had nearly 200 times the level of virus of those who did not receive the drug.

Furthermore, cocaine-fed rodents experienced significant injury to their immune systems, as well. "There was a dramatic decrease in the number of CD4+ T cells--these are one of the primary cellular immune defenders, and the target cell of choice for HIV," Baldwin said. According to the researchers, the number of CD4+ cells fell 9 times faster in rats fed cocaine versus those that were not.

The exact mechanisms behind cocaine's impact on HIV and immune health remains unclear. "There certainly are some targets we can look at," Baldwin said. "Cocaine doesn't work by itself...it has a number of byproducts, and these byproducts can act on HIV. These can include things as straightforward as cellular mediators such as cytokines, compounds which have been already shown to have an effect on HIV replication." Cocaine and its byproducts might also help HIV break into cells.

Regardless of the way in which it wreaks havoc with HIV, the message to HIV-positive individuals--or anyone else--seems clear: stay away from cocaine.

"Even if cocaine had no effect on HIV replication, the consequences of use in immune-compromised population is very straightforward," Baldwin noted. But evidence that cocaine could actually speed the spread of HIV within cells may now mean that "the caution against this sort of recreational drug use has now been increased 200-fold," she said.

Source: The Journal of Infectious Diseases, 2002:185:701-705.