Erythrocyte deformability and size measured in a multiparameter system that includes impedance sizing.

A Coulter Counter was modified to allow the photographing of erythrocytes as they exist the sizing orifice. These photographs provide the necessary information to determine the shape of individual cells. This data was combined on a cell-by-cell basis with the corresponding impedance signal to determine accurately both the cell size and deformed state of each cell. The particle shape is required if the size is to be determined accurately. Normal, diabetic and sickle cell samples were used in this study. The cell size was corrected according to theory that relates the impedance signal with cell shape. Although there was no objective test to determine the efficacy of this calculation in terms of improving the size measured, the reduction in the associated distribution width is taken as indicative of an improvement in the measuring process. The data presented represent the first attempt to relate cell size with deformed state on a cell-by-cell basis and indicates the potential usefulness of multiparameter deformability and size measurements.