Molecular and biochemical characterization of nitric oxide synthase isoforms and their intracellular distribution in human peripheral blood mononuclear cells

► PBMCs, monocytes and lymphocytes express all the three NOS isoforms (nNOS, iNOS, eNOS) at protein as well as transcript levels. ► The expression of iNOS and eNOS was predominant over other NOS isoforms in lymphocytes and monocytes respectively. ► NOS is catalytically active in PBMCs, monocytes and lymphocytes ► NOS catalysis is attributed to both calcium dependent and independent isoforms. ► Monocytes demonstrated more cytoplasmic predominance for NOS than nuclear distribution while lymphocytes exhibited almost equal distribution in both cellular compartments.