Bilirubin adsorption in vitro by foetal and adult human erythrocytes.

Adsorption of bilirubin in vitro by human foetal erythrocytes from umbilical cords was significantly greater than the binding by adult erythrocytes. A difference in binding capacity was detected at 0.6 mmol/l bilirubin concentration (bilirubin/albumin ratio 2:1) immediately after mixing with the bilirubin solution. After 30 min incubation a further increase in bound bilirubin was found to be due only to binding in foetal cells. The results suggest that bilirubin from the medium was incorporated into at least two compartments in foetal erythrocytes. A possible role of human foetal erythrocytes in bilirubin distribution to tissues is stressed.