THE INTERACTION OF MACROPHAGE AND NON-MACROPHAGE TROPIC ISOLATES OF HIV-1 WITH THYMIC AND TONSILLAR DENDRITIC CELLS IN-VITRO

Dendritic cells isolated from thymus and tonsil were tested for suscep tibility to HIV-1 strains that are tropic for macrophages or for T cel l lines. DCs were purified by cell sorting and before infection expres sed high levels of CD4 and HLA-DR and lacked markers for T, B, NK cell s, or macrophages. Viral entry and revel-se transcription was found af ter pulsing with strains of HIV-1 that could infect macrophages. Durin g the first 36 h the PCR signals for gag sequences increased in DCs an d macrophages. In contrast little if any viral DNA was found after pul sing macrophages or DCs with HIV-1 that was able to infect T cell lili es. DCs pulsed with HIV-1 were able to transmit infection to respondin g T cells during an allogeneic or superantigen response. Selection for virus able to infect lymphoid DCs and other DCs expressing CD4 and it s transfer to T cells during subsequent immune responses may provide a mechanism for the observed predominance of macrophage-tropic HIV-1 af ter in vivo transmission.