Bilirubin Binding by Human Erythrocytes

Erythrocytic binding of bilirubin was investigated by incubating the cells in solutions containing bilirubin and albumin. Bilirubin bound by the cells was then eluted with a solution of albumin. At low bilirubin concentrations the binding of bilirubin by red cells was influenced by both the total bilirubin concentration and the molar bilirubin/albumin ratio. At bilirubin concentrations above approx. 200 μmol/1, the red cell binding of bilirubin was mainly dependent on the molar bilirubin/albumin ratio. Immunized erythrocytes did not differ significantly from normal cells in their ability to bind bilirubin. Determination of erythrocyte-bound bilirubin may be of clinical significance in cases of neonatal jaundice.