Dendritic cells can enhance the replication of HIV-1 in CD4 + lymphocytes through the interaction of the gp120 envelope protein with such molecules as dendritic cell-specific intercellular adhesion molecule-3-grabbing noninte-grin. The variable loops of gp120 have previously been shown to modulate the interaction of HIV-1 with its principal receptor CD4 and its various coreceptors, namely CCR5 and CXCR4.