Cocaine boosts the ability of HIV to infect immune system cells and suppresses the production of immune system chemicals which could keep the virus under control, according to researchers from the State University of New York in Buffalo.
Although cocaine use has been linked to faster HIV disease progression in some (but not all) studies, the precise mechanism by which it might speed up HIV disease has never been understood. The Buffalo team found that production of the chemokine MIP-1beta is down-regulated when peripheral blood mononuclear cells are exposed from HIV-infected individuals are exposed to cocaine in the test-tube.
MIP-1beta regulates the expression of CCR5, a receptor on the surface of CD4 lymphocytes used by HIV to gain entry to these cells. If MIP-1beta production is slowed down, more CCR5 receptors will be available for HIV to latch onto, and the researchers also found that the presence of cocaine increased the number of these receptors that could be detected.
Cocaine may be a more important co-factor in people with less advanced HIV infection, because at this time HIV needs to use the CCR5 co-receptor. Later on however other variants of HIV will emerge which can use other co-receptors even if CCR5 is being expressed at a very low level.
Reference
Nair PNN et al. Cocaine differentially modulates chemokine production by mononuclear cells from normal donors and human immunedeficiency virus type 1 infected patients. Clinical and Diagnostic Laboratory Immunology 7:1, 96-100, 2000.