Cell cultures and calcitriol treatment

The PBMCs were isolated by a density gradient with Hystopaque reagent (Sigma-Aldrich, St. Louis, MO, USA) or Lymphoprep^™ (Alere Technologies AS, Oslo, Norway). The PBMCs, obtained from healthy donors, were treated with two concentrations of calcitriol (1x10^-8M and 5x10^-10M) or ethanol at 1% (EtOH), as vehicle control (Sigma-Aldrich) for 24 hours at 37°C and 5% CO₂. The PBMCs from HESNs were treated with only one concentration of calcitriol at 1x10^-9M due to sample limitation. PBMCs of all recruited individuals were stimulated with phytohemagglutinin (PHA) (Sigma-Aldrich) (8ug/ml) and IL-2 (50 IU/mL) (Sigma) for 48 hours, before HIV-1 infection, maintaining supplementation with calcitriol.