SAMHD1 levels in primary CD4+ T-lymphocytes are not upregulated by type I IFN treatment. Primary CD4+ T cells from two healthy donors were treated with (+) or without PHA (5 μg/mL) for 48 hr and cultured in the presence of different amounts of IFNα for 24 hr. Whole cell lysates were subjected to immunoblotting for SAMHD1 and tetherin expression. β-actin was used as a loading control and relative levels of SAMHD1 compared to β-actin are shown. The data shown represents one of three independent experiments using cells from three different donors.