Using the hemoglobin-binding Staphylococcus aureus protein IsdH to enable plasma analysis of hemolyzed blood samples.

Background Intravascular hemolysis and in vitro hemolysis are prevalent contributors to failed blood sample analysis in the routine hospital laboratory. Interferences by hemoglobin in spectrophotometric and certain enzyme activity assays is the major causative factor. Methods By exploiting the hemoglobin-binding properties of the iron-regulated surface determinant H (IsdH) protein from Staphylococcus aureus we have developed a new method to instantly remove hemoglobin and hemoglobin-haptoglobin complexes from plasma in vitro thereby enabling the measurement of hemoglobin-sensitive analytes in hemolyzed plasma.

The Staphylococcus aureus Protein IsdH Inhibits Host Hemoglobin Scavenging to Promote Heme Acquisition by the Pathogen.

Hemolysis is a complication in septic infections with Staphylococcus aureus, which utilizes the released Hb as an iron source. S. aureus can acquire heme in vitro from hemoglobin (Hb) by a heme-sequestering mechanism that involves proteins from the S.

Haptoglobin.

Haptoglobin (Hp) is an abundant human plasma protein that tightly captures hemoglobin (Hb) during hemolysis. The Hb-Hp complex formation reduces the oxidative properties of heme/Hb and promotes recognition by the macrophage scavenger receptor CD163. This leads to Hb-Hp breakdown and heme catabolism by heme oxygenase and biliverdin reductase.