The Trajectory of Haptoglobin in Haemolysis, Inflammation and Transfusion Reaction

Abstract

Introduction: Haptoglobin is an acute-phase α₂-glycoprotein produced in the liver with the major biological function of binding free haemoglobin with very high affinity to prevent the loss of iron following hemolysis. Haptoglobin has an anti-inflammatory property and is raised during inflammation whereas, low level is associated with haemolysis. Transfusion is linked with haemolysis thereby increasing the level of free haemoglobin due to anti-haptoglobin and storage effect. Studies have revealed interplay of haptoglobin in haemolysis, inflammation and transfusion reaction although, the underlying mechanism is not well understood. Besides, its utilization as a diagnostic biomarker and therapeutic advantage have not been well explored hence, this study.

Method: In this review 20 primary studies from various electronic databases such as Google scholar, Semantic scholar and PubMed were obtained on the basis that they were focused on haptoglobin, haptoglobin in haemolysis, inflammation and transfusion. This was made possible by the use of Boolean function.

Results: Haptoglobin, is measured in blood due to its complex formation with hemoglobin, forming a protective non-covalent complex with CD63 as receptor. The finding from this review shows that, haptoglobin plays a crucial role in scavenging surplus hemoglobin, iron and heme in haemolysis with antioxidant function and immunomodulatory effect in transfusion reactions. The concept of the trajectory of haptoglobin explored the multi-dimensional course of this acute phase scavenger protein in the course of clinical conditions of haemolysis, inflammation and transfusion reaction. The review confirmed specific roles of haptoglobin such as physiologic-antioxidant, prognostic, diagnostic biomarker, immunologic and therapeutic. Additionally, an inverse relationship exists between haptoglobin and haemolysis as well as transfusion reaction consequent to hypohaptogloinaemia whereas, direct relationship exists with inflammation resulting to hyperhaptoglobinaemia observed in those clinical conditions respectively. Haptoglobin synthesis is elevated by the liver in response to inflammation, countering oxidative damage and inflammation by neutralizing free hemoglobin. When there is an immunological mismatch, haemolytic transfusion reactions can occur and transfusion of prolonged stored blood potentiate same effect.

Conclusion: The role of haptoglobin cannot be overemphasized. Based on the widespread roles and clinical relevance of haptoglobin, it is vital that haptoglobin be utilized.