IN-VITRO HIV-1 INFECTION OF CD34(-DERIVED DENDRITIC LANGERHANS CELLS AT DIFFERENT STAGES OF THEIR DIFFERENTIATION IN THE PRESENCE OF GM-CSFTNF-ALPHA() PROGENITOR)

Langerhans cells (LC) are antigen-presenting cells which are found in areas at risk of inoculation by the human immunodeficiency virus (HIV) . LC were shown to be sensitive to in vitro infection by HIV1. They co uld be generated in vitro by culturing CD34(+) haematopoietic progenit ors with GM-CSF+TNF alpha. In this study, we tested the sensitivity to HIV1 infection of in vitro generated LC throughout their differentiat ion and we investigated the effect of such an Infection on in vitro di fferentiation. Phenotypic controls were performed using FACS analysis on day 6 for the presence of a CD1a(+) cell population, and differenti ation was assessed by transmission electron microscopy on day 13 for t he presence of Birbeck granules. CD34(+) cells were purified from cord blood mononuclear cells by magnetic separation. Cell suspensions were infected with either a T-lymphotropic, syncytium-inducing isolate (HX B2) or a macrophage-tropic, non-syncytium-inducing isolate (Ba-L). Vir al particle release was measured by p24 antigen production in the cult ure supernatant. A high level of p24 production was noted on day 13 of postinfection only when infection was carried out with Ba-L isolate o n cells generated after 6 days in culture with GM/CSF+TNF alpha. No in fection of CD34(+) progenitor cells was obtained either with Ba-L isol ate or HXB2. The sensitivity of Langerhans cell/dendritic cell (LC/DC) precursors to NSI isolate (Ba-L) seemed to coincide with the early st age of differentiation (CD1a antigen appearance). The infection did no t alter the differentiation of in vitro generated LC, which presented their specific ultrastructural marker of epidermal environment, i.e. B irbeck granules from day 15 of the culture as compared to control cult ure. These results highlight the HIV infectibility of a differentiated population of LC/DC generated in vitro from CD34(+) progenitors.