Complement factor H levels in steady state sickle cell anaemia

Abstract

Objective: The red cell membrane of sickle cell anaemia is vulnerable to attack from the alternative complement pathway. The activation of the alternative complement pathway is initiated by externalization of phosphatidylserine on red cell membrane. Serum and cell bound regulators normally prevent amplification of the cascade. However, red blood cells in sickle cell anaemia appear to be exposed and the cell lysing membrane attack complex is ubiquitous on irreversible sickle red blood cells. It is possible that there are deficiencies (either functional or quantitative) of complement regulators. In this study the quantitative defects of the most abundant serum phase regulator, complement factor H in sickle cell anaemia was investigated. Methods: We compared the plasma levels of complement factor H (a serum phase regulator of the alternative pathway) in 61 steady state Hb SS with 60 healthy Hb AA using an enzyme linked immunosorbent assay to analyze complement factor H level in the plasma. The full blood count parameters were estimated using flow cytometry. Results: There was no significant difference in the serum complement factor H levels between the steady state Hb SS and healthy Hb AA. Significant inverse relationships existed between complement factor H, total white cell count, granulocyte cell count and platelet count as well as significant direct relationships between complement factor H, haematocrit, and the haemoglobin concentration. Conclusion: Complement factor H in patients with sickle cell anaemia who are in steady state is not significantly lower than in controls.