Activity of reverse transcriptase inhibitors in monocyte-derived dendritic cells: a possible in vitro model for postexposure prophylaxis of sexual HIV transmission.

Because prevention of heterosexual HIV transmission is not always possible, it is important to develop effective strategies of postexposure prophylaxis (PEP). Since in vivo comparison of drug potency is difficult, we developed an in vitro model with cells resembling primary targets during sexual transmission: monocyte-derived dendritic cells (MO-DCs), Langerhans cells (MO-LCs), and resting autologous CD4(+) T cells. Nucleoside and nonnucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs, respectively) were evaluated for their antiviral activity, when added immediately after infection or at a later time point. In parallel, their immune-suppressive effect was examined by measuring inhibition of mixed MO-DC/allogeneic CD4(+) T cell cultures. Most RTIs potently inhibited HIV replication, even if added 24 hr after infection (representing PEP). The sensitivity to antiretroviral drugs was similar in HIV-infected MO-DCs and MO-LCs, but decreased in cocultures with resting autologous CD4(+) T cells. The NNRTIs efavirenz and UC-781 as well as the NRTIs AZT, 3TC, and d4T showed a similar high potency in MO-DC plus autologous CD4(+) T cell cocultures as compared with CEM T cells, whereas their activity in phytohemagglutinin/interleukin 2 (PHA/IL-2)-activated CD4(+) T cells was lower. The dideoxynucleoside RTI abacavir as well as the phosphonates (R)-PMPA and PMEA were more active in infected MO-DCs as compared with either CEM T cells or PHA/IL-2 activated CD4(+) T cells. Infection in cocultures of MO-DCs and autologous CD4(+) T cells could be aborted in a proportion of the cultures, with high concentrations of PMEA and/or efavirenz, but not with AZT. Suppressive activity in mixed leukocyte cultures was observed only at very high concentrations of RTI. Our data suggest that cocultures of MO-DCs and autologous CD4(+) T cells can be used as a possible in vitro model to explore protocols for PEP after sexual HIV transmission.