Ligand state of intraerythrocytic circulating HbC crystals in homozygote CC patients.

Whole blood and Stractan-Percoll fractions of blood from splenectomized patients with homozygous hemoglobin C (CC) disease were studied under aerobic and anaerobic conditions. Erythrocytes containing typical CC crystals are found in the densest fraction as documented by freeze-fracture electron microscopy. We report that the intraerythrocytic Hb C circulating crystals are in the oxygenated liganded state as demonstrated by melting upon deoxygenation and by absorption spectroscopy. Furthermore, crystals are more likely to form in cells with low concentration of Hb F. Changes of ligand state (which results in melting of the intraerythrocytic crystal) might be involved in the pathophysiology of this disease, removing the danger of vasoocclusive episodes.