By Drs. David Niesel and Norbert Herzog
Cocaine and HIV Infection
It is well known that cocaine use increases the chance of acquiring HIV, the virus infection that if left untreated leads to AIDS. It was assumed that needle sharing and increased risky behaviors were the reason for more infections. Some data now argues that cocaine use fundamentally changes cells of the immune system making them more susceptible to HIV infection.
HIV is a retrovirus that infects cells of the immune system that carry the receptors to which HIV binds on their surfaces. The cells are a type of white blood cells called a T lymphocyte or T cell. T cells are important in identifying and hunting down virus infected cells and some of them are critical in orchestrating the immune response. For HIV to successfully infect the T cells, they must be capable of dividing into daughter cells. A large population of T cells in the body are not dividing and hence dormant and HIV cannot infect them.
Anything that activates these dormant cells would increase the cells HIV could infect. Scientists exposed dormant T cells to cocaine and then to HIV. They measured the amount of HIV produced to determine if cocaine influenced the susceptibility of these dormant cells to HIV infection. Exposure to cocaine increases the susceptibility of dormant T cells to HIV infection. These experiments were done in a petri dish, but if this occurs in the body, this would greatly increase the number of cells available for HIV to productively infect in cocaine users. This would increase the likelihood of establishing an HIV infection, likely making the infection more severe and potentially affecting the disease progression.
More recently, the investigators did similar experiments but this time in a very special type of mouse called a humanized mouse. In these mice, their immune system was eliminated and replaced with a human one. This was done by transplanting stem cells that become the full range of human immune cells, making in effect a mouse with a human immune system. These mice are a good model for studying HIV infections and their impact on the immune system. They had two groups of mice, one was injected with cocaine, and a control group that just received injections of saline before half the mice in each group were infected with HIV. Then the mice continued to receive either cocaine or saline for two more weeks after which blood and tissue samples were analyzed. HIV infected mice that received cocaine were found to have higher levels of virus than their counterparts which received only saline. So cocaine exposure enhances HIV infection and makes the infection worse, exactly as predicted by the petri dish experiments. They also discovered that cocaine reduced the immune response to HIV infection by affecting the activities of the very cells that usually protect us from viral infections. So cocaine not only changes people's behaviors, but also changes the cells of the immune system increasing the chances of HIV infection and potentially the severity of it. Cocaine is a tremendously addictive drug that ruins lives and now we know another important way it can compromise your health. Stay away!
Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.