Patent ID: 6228652
Filing Date: 2001-05-08
Classification: G01N,Y10S,Y10T

Abstract:
Apparatus for differentiating and enumerating various types of blood cells in a whole blood sample, said apparatus comprising:(a) a single flow cell comprising an optically transparent element in the form of a rectangular prism defining a passageway through which formed bodies in said sample can be made to pass one at a time, said passageway defining a cell-interrogation zone having a substantially square transverse cross-section, determined perpendicular to the direction of blood cell flow, of approximately 50 microns on each side and a length of approximately 65 microns, measured in the direction of blood cell flow;(b) means for aspirating a sample of whole blood from a container;(c) means for producing at least a first aliquot of the aspirated whole blood sample;(d) means for subjecting the first aliquot of whole blood to a lysing reagent to provide a lysed sample containing predominantly white blood cells and nucleated red blood cells;(e) means for subjecting one or more subsets of cells contained in the lysed sample to a fluorescent material, thereby causing said subsets of cells to become labeled with such fluorescent material;(f) metering means for producing a metered volume of the lysed sample;(g) means for causing said metered volume of said lysed sample to flow through the cell-interrogation zone of the flow cell so that blood cells in said metered volume flow through said cell-interrogation zone seriatim;(h) circuit means for (a) simultaneously establishing DC and RF current flows through said cell-interrogation zone while blood cells are flowing therethrough, each of said blood cells being effective to (i) modulate the DC current in said zone as a function of the cell's volume, and (ii) modulate the RF current flow in said zone as a function of the cell's internal conductivity; and (b) detecting modulations in said DC and RF currents;(i) optical means for irradiating individual blood cells flowing through said cell-interrogation zone with a beam of radiation propagating along an axis perpendicular to the direction of sample flow, said radiation being adapted to cause the fluorescent material to fluoresce;(j) radiation scatter-detecting means for detecting radiation scattered from an irradiated blood cell in said zone;(k) fluorescence-detecting means for detecting radiation fluorescing from a fluorescent material-labeled subset of cells as a result of being irradiated by said optical means; and(l) analyzing means, operatively coupled to said circuit means and to the respective radiation scatter- and fluorescence-detecting means, for differentiating and determining the respective concentrations of different subsets of white cells and fluorescent material-labeled cells based upon their respective DC volume (V), RF conductivity (C), light scatter (S) and fluorescence (F) properties.