Sickle cell crisis and some properties of the circulating erythrocytes

The cause for the occurrence and resolution of sickle cell crisis (SCC) is not known. Crisis is an episodic event while the molecular abnormality is constant. The authors studied red cell properties serially in 8 episodes of SCC in patients homozygous for hemoglobin S. The studies included time of filtration (TF), % filtered cells (F) and % sickled cells (SC). Observations were made at 24-72 hr, intervals until recovery. Fresh RBCs at 2g%Hb concentration in a NaCl KCl PO₄ buffer, pH 7.2 at 37°C were oxygenated (10') and then slowly deoxygenated (120') with monitoring of the HbO₂ concentration. Filtration was achieved through 3μ Nuclepore filters. With recovery from crisis there was a consistent decrease in TF and SC and a consistent rise in F. One patient observed prior to SCC showed a progressive increase in TF and SC and a progressive decrease in F preceeding the development of overt crisis. The study demonstrates that recovery from SCC correlates with: increased filterability of RBCs as measured by TF and F (p < 0.02), and decreased susceptibility of circulating RBC to sickle (p < 0.02). A decrease of red cell DPG was noted in 5 of 7 episodes by an average of 29.0% (p < 0.05). It is suggested that these changes are causally related to the occurrence and resolution of SCC.