Levels of antigen processing machinery components in dendritic cells generated for vaccination of HIV-1+ subjects

To evaluate expression of the antigen processing machinery (APM) components and HLA molecules by monocyte-derived dendritic cells (DC) generated from chronically HIV-1 infected subjects on antiretroviral therapy (ART) and to assess their ability to ex vivo induce HIV-1 specific T cells.

DC generated in 16 HLA-A2 positive patients were matured in cytokines, pulsed with HIV-1 or other viral peptides and tested in interferon (IFN)-gamma ELISPOT assays. Immature (i)DC, mature (m)DC and viral peptide-pulsed DC were studied by multiparameter quantitative flow cytometry for intracellular APM component expression and for HLA class I and II, beta-2 microglobulin and co-stimulatory molecule surface expression. DC from 13 normal donors served as controls.

Marked heterogeneity in APM component expression levels in iDC and mDC from HIV-1 positive subjects was observed. Nevertheless, the median levels were comparable to those in iDC and mDC, respectively, from normal donors. Patients' mDC pulsed with the HIV-1, influenza A, cytomegalovirus (CMV) or Epstein-Barr virus peptides induced IFN-gamma production by T cells specific for these peptides in ELISPOT assays. The frequency of T cells responsive to influenza A, cytomegalovirus or Epstein-Barr virus peptides was comparable in the patients and normal donors.

The APM component expression profiles of iDC and mDC were more heterogeneous in subjects with chronic HIV-1 infection on ART, than those in normal donors, although not statistically different. Ex vivo, patients' DC pulsed with HIV-1 peptides induced IFN-gamma production from autologous T cells. Thus, DC obtained from HIV-1 infected subjects on ART were phenotypically and functionally competent.