C2/LILRB4 protein level ratio in blood (Ontology of Biological Attributes term OBA_2053178) can be described as follows. A compound attribute that is the ratio of amount of complement C2 (human) in blood to amount of leukocyte immunoglobulin-like receptor subfamily B member 4 (human) in blood. Also known as: the ratio of amount of complement C2 (human) in blood to amount of leukocyte immunoglobulin-like receptor subfamily B member 4 (human) in blood.