Ontology of Biological Attributes identifier OBA_2054042 (PDCD1/TNFRSF9 protein level ratio in blood) can be described as follows. A compound attribute that is the ratio of amount of programmed cell death protein 1 (human) in blood to amount of tumor necrosis factor receptor superfamily member 9 (human) in blood. Also known as: the ratio of amount of programmed cell death protein 1 (human) in blood to amount of tumor necrosis factor receptor superfamily member 9 (human) in blood.