Solidity of sickle hemoglobin gels: relevance to pathophysiology of sickling disorders

The physical properties of hemoglobin (Hb) S gels formed under conditions relevant to in vivo conditions have been characterized using viscometry. Mixed Hb SF and Hb AS gels of hemoglobin concentrations and compositions found in patients with Hb S-HPFH (mild sickle-cell disease) and Hb AS (sickle-cell trait) have been compared to those of pure Hb S. The results may explain why red cells containing gels occlude the microcirculation and/or undergo hemolysis in patients with sickle-cell anemia, why patients with Hb S-HPFH are mildly affected with red-cell sickling, and why individuals with Hb AS have no clinical manifestations of the Hb abnormality.