Detection of HIV-specific DNA sequences in epidermal Langerhans cells infected in vitro by means of a cell-free system

Human immunodeficiency virus type 1 strains of subtypes B and E replicate in cutaneous dendritic cell-T-cell mixtures without displaying subtype-specific tropism

A report that genetic subtype E human immunodeficiency virus type 1 (HIV-1) strains display a preferential tropism for Langerhans cells (epidermal dendritic cells [DCs]) compared to genetic subtype B strains suggested a possible explanation for the rapid heterosexual spread of subtype E strains in Thailand (L. E. Soto-Ramirez et al., Science 271:1291-1293, 1996). In an independent system, we applied subtype E and B isolates to skin leukocytes, since skin is a relevant model for the histologically comparable surfaces of the vagina and ectocervix. Isolates of both HIV-1 subtypes infected DC-T-cell mixtures, and no subtype-specific pattern of infection was observed. Purified DCs did not support the replication of strains of either subtype B or E. Our findings do not support the conclusion that subtype E strains have a preferential tropism for DCs, suggesting that other explanations for the rapid heterosexual spread of subtype E strains in Asia should be considered.

Role of dendritic cells in immunopathogenesis of human immunodeficiency virus infection

The role of dendritic cells (DC) in the pathogenesis of human immunodeficiency virus (HIV) disease has been a subject of considerable interest for several years. Initial studies focused on the infection, dysfunction, and depletion of DC in HIV-infected individuals. More recent studies have begun to identify the functional role of DC in the initiation and propagation of viral replication in T cells in HIV-infected individuals. This review discusses recent data regarding the role of DC in HIV disease with the aim of delineating basic immunopathogenic principles of infection and the development of therapeutic strategies.

In vitro HIV1 infection of CD34+ progenitor-derived dendritic/Langerhans cells at different stages of their differentiation in the presence of GM-CSF/TNF alpha

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 could be generated in vitro by culturing CD34+ haematopoietic progenitors with GM-CSF+TNF alpha. In this study, we tested the sensitivity to HIV1 infection of in vitro generated LC throughout their differentiation and we investigated the effect of such an infection on in vitro differentiation. Phenotypic controls were performed using FACS analysis on day 6 for the presence of a CD1a+ cell population, and differentiation was assessed by transmission electron microscopy on day 13 for the 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 (HXB2) or a macrophage-tropic, non-syncytium-inducing isolate (Ba-L). Viral particle release was measured by p24 antigen production in the culture supernatant. A high level of p24 production was noted on day 13 of postinfection only when infection was carried out with Ba-L isolate on cells generated after 6 days in culture with GM/CSF+TNF alpha. No infection of CD34+ progenitor cells was obtained either with Ba-L isolate or HXB2. The sensitivity of Langerhans cell/dendritic cell (LC/DC) precursors to NSI isolate (Ba-L) seemed to coincide with the early stage of differentiation (CD1a antigen appearance). The infection did not alter the differentiation of in vitro generated LC, which presented their specific ultrastructural marker of epidermal environment, i.e. Birbeck granules from day 15 of the culture as compared to control culture. These results highlight the HIV infectibility of a differentiated population of LC/DC generated in vitro from CD34+ progenitors.