Human PD-1 ELISA Kit PicoKine® (96 Tests) . Quantitate Human PDCD1 in serum and plasma (heparin) . Sensitivity: 10pg/ml. The brand Picokine indicates this is a premium quality ELISA kit. Each Picokine kit delivers precise quantification, high sensitivity, and excellent reproducibility. Only our most reliable and effective kits qualify as Picokine, guaranteeing top-tier results for your assays.