The history, diagnosis, and pathophysiology of human immunodeficiency virus and acquired immunodeficiency syndrome

The history of human immunodeficiency virus (HIV) is important to the immunologist as the immune deficiency was recognized long before the virus responsible for acquired immunodeficiency syndrome (AIDS) was identified as a retrovirus and named the HIV. The HIV virus, if uncontrolled, causes the AIDS by depletion of CD4+ T cells, and our understanding of the normal ranges for CD4+ T cells in infants, children, and adults stems from our investigations of HIV. The depletion of the CD4+ T cells causes a slow deterioration of immunity and immune regulation leading to a cascade of immune deficits and opportunistic infections. Early in infection CD8+ T cells may help control infection, but if untreated the infection eventually leads to dysregulation of CD8+ T cells and eventually dysregulation of B cells. An inability to make antibody is a late manifestation of AIDS. The HIV infection presents and progresses differently in infants and children than it does in adults and the infection in infants progresses more rapidly and leads to faster immunological and neurological deterioration if untreated. In the era of potent and reliable antiretroviral therapy it is reasonable to predict that AIDS will become less and less common as HIV testing is offered routinely, and nearly all cases of HIV are detected very early before damage to the immune system has occurs. Treatment as prevention and postexposure prophylaxis are discussed in this chapter. Hypersensitivity reactions that have historically been more common in HIV are also discussed, as they are particularly important to the immunologist.