CD40/CD40LG protein level ratio in blood (OBA_2054199, an Ontology of Biological Attributes id) can be described as follows. A compound attribute that is the ratio of amount of tumor necrosis factor receptor superfamily member 5 (human) in blood to amount of CD40 ligand (human) in blood. Also known as: the ratio of amount of tumor necrosis factor receptor superfamily member 5 (human) in blood to amount of CD40 ligand (human) in blood.