evidence: In the past 20 years, a handful of people have been cured of human immunodeficiency virus (HIV), the virus that causes AIDS, through intensive medical procedures. Several more people have received the treatment and also appear to be HIV-free, but it's too soon to definitively declare these patients cured. For now, they're described as being in long-term remission, and their cases are considered "possible" cures. All these patients received stem cell transplants, with cells collected either from adult bone marrow or from umbilical cord blood. [...] All of the people cured and potentially cured of HIV have been treated with stem cell transplants. In addition to being HIV-positive, all the patients had some form of cancer, typically acute myeloid leukemia or Hodgkin's lymphoma. These cancers affect white blood cells, a key component of the immune system, and can be treated with stem cell transplants.