THE EFFECT OF IN-VITRO HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION ON DENDRITIC-CELL DIFFERENTIATION AND FUNCTION

CD1a(+) dendritic cells (DC) differentiate from a major population of nonadherent CD13(h-)lin(-) cells that appear when human cord blood CD3 4(+) hematopoietic progenitor cells are cultured with stem-cell factor , granulocyte/macrophage (MA) colony-stimulating factor, and tumor nec rosis factor-alpha (TNF-alpha) for 5 days. CD13h--(-)(lin) cells, whic h also comprise MA and granulocyte precursors, are CD4(+) and can thus be targets of human immunodeficiency virus (HIV). Low replication was noted when these day 5 cells were infected with lymphotropic HIV-1(LA I) (p24: less than or equal to 4 ng/mL on day 8 postinfection [PI]), w hile high virus production occurred with MA-tropic HIV-1(Ba-L), HIV-1( Ada), or HIV-1(JR-FL) (p24: 50 to greater than or equal to 1,000 ng/mL ). Strong cytopathicity (CPE) was then observed in nonadherent cells a s in adherent MA. However, FACS analysis on day 7 PI showed that HIV d id not affect differentiation of DC that survived CPE: apart from CD4 downmodulation related to HIV production, overall expression of CD40, CD80, and CD86 costimulatory molecules, and of HLA-DR, was unchanged r elative to controls. At that time, the capacity of DC from HIV-infecte d cultures to stimulate the mixed leukocyte reaction was only altered less than 10-fold. Immunocytochemistry on day 7 PI showed that most HI V-infected cells were included in syncytia that were stained by anti-C D1a, anti-S100, and anti-CD14 antibodies, indicating that syncytia con sisted of DC and cells of the MA lineage. Polymerase chain reaction an alysis of FACS-sorted CD1a(+) cells confirmed that they harbored then HIV DNA. Viral DNA was also detected in CD1a(+) DC from noninfected cu ltures that had been exposed to HIV only after sorting. Therefore, we examined whether in infected cultures DC precursors were infected at t he onset or if virus spread later from other infected cells to differe ntiated DC. This was answered by showing that, 24 hours postexposure t o HIV, viral DNA was preferentially detected in day 5 sorted CD13(hi)l in(-) versus CD13(low)lin(-) cells, and that it was found in the CD1a( +) progeny of CD13(hi)lin(-) cells 48 hours later. In addition, HIV re plication did not affect myeloid clonogenic progenitors in day 0 to da y 7 PI cultures, although viral DNA was detected in colony-forming uni t-granulocyte/macrophage (CFU-GM)/CFU-M colonies derived from day 3 an d 7 PI cultures. Thus, precursors of DC and their progeny are suscepti ble to HIV in vitro, but, apart from CPE, the effect of virus producti on on DC differentiation or function is limited. (C) 1996 by The Ameri can Society of Hematology.