A convenient and reproducible filtration technique for the determination of erythrocyte flexibility.

A micro-cell filtration technique is described in which a silver membrane of 3 mum porosity is used. The apparatus consists of a membrane holder and disposable syringe only. A regeneration procedure which allows indefinite re-use of one membrane is described. Filtration proceeds under the hydrostatic pressure of the fluid column only. A locke-albumin solution has been developed as a suspension medium and adapted for cell washing by the addition of fibrinogen and cholesterol. A plot of the volumes of cells filtered against log time shows a linear relationship for normal erythrocytes. The filtered red cells are virtually undamaged. The overall precision of the method of the order of +/-2%.