Impaired echinocytic transformation of ankyrin- and spectrin-deficient erythrocytes in mice.

The membrane skeleton of the red blood cell plays an important role in the determination of cell deformability and cell shape. Under various in vitro conditions, red blood cells undergo an echinocytic or stomatocytic shape transformation. The mechanism of this fundamental process is not well understood. We have studied the red cell shape transformation in normoblastic anemia mice (nb/nb) and spherocytic anemia mice (sph/sph), which are deficient in ankyrin and spectrin, respectively. We found that both ankyrin-deficient cells (nb/nb) and spectrin-deficient cells (sph/sph) have a reduced capacity to undergo echinocytic transformation with various echinocytogenic treatments, that is, incubation with sodium salicylate (40 and 120 mM), calcium loading (50 microM A23187 + 2.2 mM Ca2+), or metabolic depletion (24 hr at 37 degrees C). These results suggest that the functional integrity of the membrane skeleton is essential for the maintenance and transformation of the red cell shape.