Macrophages in the human body act a reservoirs of  HIV. HIV infects the cells of the body and replicates in the host cells generating more HIV. However, the macrophages are latent and act as storehouses of HIV that do not replicate in these cells. When HIV are present in the cells in a latent form, the virus in the cells can hide in the cells for a long time(e.g: when a patient is taking medicines to destroy the virus).