Intracellular Ca(2+)-containing vesicles in sickle cell disorders

The frequency of red blood cells harboring Ca(2+)-containing vesicles was determined in patients with various sickle cell disorders; vesicles were identified by microscopy after the cells were stained with the fluorescent probe chlortetracycline. Specimens from 49 patients were studied. The highest frequencies of vesicle-containing cells were observed in samples from adults with homozygous sickle cell (SS) disease and in patients with S beta zero and SS(-alpha/alpha alpha) thalassemias. The frequency of cells with vesicles was less elevated in patients with SS(-alpha/-alpha) thalassemia and in patients with SS disease (Saudi Arabia high hemoglobin F), whereas a normal low frequency of positive cells was seen in patients with sickle cell-hereditary persistence of fetal hemoglobin and in patients with sickle trait. Deoxygenation induced an increase in the number of vesicle-containing cells that was proportional to the frequency of such cells in the oxygenated population. The frequency of Ca(2+)-containing vesicles in sickle red cells is associated with the clinical, hematologic, or clinical and hematologic severity of the sickle cell disorder.