A compound attribute that is the ratio of amount of butyrophilin subfamily 2 member A1 (human) in blood to amount of macrophage colony-stimulating factor 1 (human) in blood. The trait is Ontology of Biological Attributes identifier OBA_2053165 (BTN2A1/CSF1 protein level ratio in blood). Also known as: the ratio of amount of butyrophilin subfamily 2 member A1 (human) in blood to amount of macrophage colony-stimulating factor 1 (human) in blood.