Introduction Osmoscan

The LoRRca MaxSis has an optional equipment with the possibility for automatic measurement of Red Blood Cell (RBC) deformability (expressed as elongation index, EI) as a continuous function of suspending medium osmolality. Both the shape and the position along the osmolality axis of specific features of these, so called osmoscans provide information about the cell`s deformability (at the chosen shear stress) as well as their intracellular viscosity and surface-volume ratio. For characterization of each osmoscan 4 parameters are defined: Omin (the osmolality at the EI minimum found in the hypotonic region), EImax (the maximal EI of the total curve), Omax (the osmolality at EI-max) and Ohyper (the osmolality in the hypertonic region corresponding to 50% of the EI-max).

Application of this approach to a variety of RBC disorders generally confirmed previously reported results obtained with first generation ektacytometers. Abnormal osmoscans, i.e. values for Omin, Omax, Ohyper and/or EImax different from normal, were found in the following hematologic disorders: Hereditary Spherocytosis, Stomatocytosis, Pyknocytosis, Hereditary Elliptocytosis, Sickle Cell anemia and Thalessemia.

Furthermore, a RBC variant in the genetic polymorphism LELY for the membrane protein Spectrin in combination with the mutation for Hereditary Elliptocytosis (HE) which can result in the dual mutated Hereditary Pyropoikilocytosis (HE-LELY), was investigated.

Osmoscans obtained after various experimental manipulations (heat treatment, exposure to shear stress and glutaraldehyde) of normal RBC, demonstrating the expected effects.