Simultaneous quantitation of free haptoglobin and haemoglobin-haptoglobin (HbHp) complexes by double-decker rocket immunoelectrophoresis.

Existing immunochemical methods for haptoglobin (Hp) determination are incapable of distinguishing between free haptoglobin and haemoglobin-haptoglobin (HbHp) complexes. A one-dimensional double-decker rocket immunoelectrophoretic method (DD-RIE) for simultaneous quantitation of free Hp and Hp bound as HbHp complexes was therefore developed. The DD-RIE can be used for quantitative in vitro studies of the Hb-Hp interactions, for quantitation of Hp's Hb binding capacity and for investigations of haemolytic episodes in patients. The clinical value of the method is illustrated by an investigation of a patient with a gradual accumulation of HbHp complexes in plasma, a steady rise in total Hp and a fall in free Hp during haemolysis. A proposed receptor-mediated clearance of the complexes by the reticuloendothelial system (RES) could not be substantiated, as HbHp receptors were not demonstrable on human blood monocytes.