FIG. 2.

Replication and intercellular transmission of HIV-1 is increased during antigen presentation. Macrophages serve as long-lived reservoirs of HIV-1 infection. During antigen presentation (both HIV-1 antigens and other antigens), activation of macrophages and CD4⁺ T lymphocytes leads to potent upregulation of proinflammatory cytokine secretion and HIV-1 transcription. This provides the ideal microenvironment for transmission of HIV-1 to CD4⁺ cells and for rapid HIV-1 replication in an expanding pool of activated memory (CD45RO⁺) cells. Selective infection of antigen-specific memory CD4⁺ cells may also lead to selective loss of this clone of cells.