Hypotonic exchange-loading of erythrocytes. II. introduction of hemoglobins S and C into normal red cells.

A rapid, simple technique whereby erythrocytes transiently exposed to hypotonic hemoglobin preparations undergo exchange of endogenous for exogenous hemoglobin has now been applied to normal, hemoglobin A-containing erythrocytes into which hemoglobin S or hemoglobin C have been introduced. Erythrocytes containing an average of 12 to 61 percent of hemoglobin S undergo sickling when incubated in isotonic dithionite solution and are morphologically indistinguishable from natural sickle cells. Ultrastructural studies of thin sections of these artificial sickle cells show microfialments and fascicles which appear typical of microtubular tactoids of hemoglobin S seen in natural sickle cells. Erthrocytes containing 43 percent introduced hemoglobin C developed all of the morphologic alterations associated with intra-erythrocytic hemoglobin C, including hemoglobin aggregation, targetting, and intracellular crystallization, after inclbation for 24 hours in isotonic saline: dithionite. The results support the concept that the sickling process, and morphologic erythrocyte alterations occurring in hemoglobin C disorders are primary to the respective hemoglobins rather than the membrane. They also suggest that any role played by the inner surface of the erythrocyte membrane in the development of these alterations is probably secondary and not specific to the inner membrane surface of the natural sickle cell or hemoglobin C-containing cell.