CD31 expression profiles and gating strategy used to purify CD31⁺ and CD31⁻ naive CD4⁺ T-cell subsets from adult and cord blood. CD4⁺ T cells were negatively selected using the EasySep Human CD4⁺ T-cell Enrichment Kit and stained using monoclonal antibodies for CD45RA, CD45RO, CD4, and CD31. Flow cytometry profiles of CD4⁺ T cells stained for CD45RA and CD31 are shown for representative adult (A) and cord blood (B) samples. Also shown is the gating strategy used for FACS sorting. After gating on viable lymphocytes and CD4⁺ T cells, cells were gated on CD45RA⁺ and CD45RO⁻ expression followed by tight gates on CD31⁺ and CD31⁻ cells as illustrated by the resulting postsorting profiles.