At the early stages of HIV disease, uninfected white blood cells hold the virus in check. Over time, those cells grow less responsive, the virus proliferates and the immune system collapses. To see if IL-12 might slow this cycle, the NCI researchers first drew blood from 40 infected volunteers and gauged their white-cell responses to a range of foreign substances. Left unassisted, the volunteers’ white cells responded sluggishly. But when the researchers added IL-12 to the blood, they got vigorous responses to the same foreign materials. “In the test tube,” says immunologist Gene Shearer, “this is the most powerful immune-response modulator we’ve seen.”
Next year researchers will start testing IL-12 for toxicity in people with HIV. If it proves safe, future studies will gauge its ability to delay or reverse the destruction of the immune system. AIDS research is littered with test-tube findings that fell short of their promise. But last week’s findings offer another glimmer of hope.
