Abstract: A method for preparing treated naturally occurring or synthetic particles using a blood cell processor is provided. The method comprises adjusting the blood cell processor to allow a dispersion of such particles to come into contact with a treatment material in an amount and for a period of time sufficient to modify all or a portion of the surface of such particles. In a preferred embodiment, the method comprises washing collected red blood cells; separating a selected volume of said washed red blood cells; and treating one portion of said separated washed cells with a selected proteolytic enzyme, to prepare a red blood cell reagent.

Abstract: A stabilized proteolytic solution has been developed which can be used to treat selected cells, especially red blood cells. A preferred stabilized solution of the invention comprises about 0.1% to about 0.3% ficin in a citrate-buffered saline solution containing mannitol, L-cysteine, dithiothrietol in an active concentration of less than about 10 mM, and EDTA. A kit for qualitatively identifying unexpected blood group antibodies comprising a series of untreated and ficin-treated red blood cells, a stabilized ficin reagent, a red blood cell diluent and an enzyme control is also provided.