Patent ID: 8889362

Claim:
An internal quality control method for determining antibody binding capacity when counting CD4+ lymphocytes in a blood sample containing monocytes and granulocytes, the method comprising the steps of: a. reacting a reagent comprising a labeled antibody specific to the CD4 cell surface antigens with a first portion of a blood sample; b. analyzing by flow cytometry first signals in the form of a first dot plot from said labeled antibody reacted with the CD4 cell surface antigens on the lymphocytes and monocytes and differentially determining whether said signals emanate from lymphocytes or monocytes to determine a position of a first monocyte cluster; c. determining a first X-Y coordinate position of the first monocyte cluster; d. analyzing by flow cytometry second signals in the form of a second dot plot from a non-labeled second portion of the blood sample, and differentially determining whether said signals emanate from lymphocytes or monocytes to determine a position of a second monocyte cluster; e. determining a second X-Y coordinate position of the second monocyte cluster; f. determining a cluster that has not shifted position form by comparing the first dot plot with the second dot plot, thereby identifying a cluster of granulocytes; and g. determining a shift in the position of the labelled monocyte cluster from the position of the non-labelled monocyte cluster by comparing the first and second X-Y coordinate positions; thereby determining the activity of said labeled antibody and eliminating the need for an external control.