Serum haptoglobin in clinical biochemistry: change of a paradigm.

Serum haptoglobin (Hp) was discovered by Max Fernand Jayle as a young assistant professor in the Department of Biochemistry of the Paris Medical Faculty, headed by Professor Michel Polonovski. Jayle showed that Hp was an acute phase glycoprotein and worked out its routine determination in the blood-serum, based on its complex formation with hemoglobin, using the increased peroxidase activity of the hemoglobin-haptoglobin (Hb-Hp) complex, for routine determination in clinical biochemistry for the characterisation of inflammatory processes, together with other acute phase glycoproteins as orosomucoide. Later Smithies described the genetic control of human Hp-isoforms and quite recently Andersen et al. reported the elucidation of the crystal structure of the porcine Hb-Hp complex. In that article there was no mention of the discovery of Hp, neither of its determination in clinical biochemistry as an inflammatory marker. The only biologically significant role assigned to Hp by Andersen et al. is its (hypothetical) role to prevent or minimize the harmful effects of Hb during intravascular hemolysis, by the generation of reactive oxygen species (ROS) and complexing it. This shift of paradigm, not at all exceptional in medical biochemistry, will be described and discussed with its pitfalls and consequences.