Patent ID: 7998696

Claim:
A method for assaying a cell sample to determine a concentration of cells of a given type in the sample, comprising: (a) adding to a cell sample containing cells of the given cell type, a given quantity of particles which specifically react and bind to the given type of cells, and being effective, when bound to the cells, to allow particle-bound cells and free particles to be separated from non-particle bound cells in the sample based on their greater density or magnetic susceptibility, which allows them to migrate selectively through a selected medium under the influence of force acting on the particles, (b) causing the particle-bound cells and particles in the cell sample to migrate through a microchannel column containing the selected medium, by subjecting the sample to such force for a period of time sufficient to cause the particle-bound cells and particles, but not non-particle-bound cells, to migrate to the bottom of the column, where the added particles make an appreciable contribution to the volume of the particle-bound cells and particles that migrate to the bottom of the column, and account for a known volume in the column, and (c) determining the volume of cells of the given type in the sample by measuring the column height of particle-bound cells and particles that migrated to the bottom of the column in step (b), where the measured column height is adjusted by the known volume of particles in the column, and where the volume determined from the adjusted column height equates to the concentration of cells of the given type in the sample.