The macrophage in HIV infection.

Macrophages play a key role in several critical aspects of HIV disease. They appear to be the first cells infected by HIV and perhaps the very source of HIV production when CD4+ cells are markedly depleted in the patient. Macrophages and microglial cells are the cells infected by HIV in the CNS. In tonsils and adenoids of HIV-infected patients, macrophages fuse into multinucleated giant cells that produce copious amounts of virus. Finally, opportunistic pathogens can cause an upregulation of HIV production by macrophages, often in the multinucleated form.