Abstract: A method for analyzing a pathological deviation of at least one white blood cell population from a normal level in an un-lysed blood sample, comprising the steps of counting, with a flow cytometer, a number, n1, of white blood cells expressing a first marker; a number, n2, of white blood cells expressing a second marker, and a number, n3, of white blood cells expressing a third marker but not the first marker; and comparing the sum (n1+n2+n3) with a reference value. The sum (n1+n2+n3) may represent the number of lymphocytes. The first, second and third markers may be chosen from the group consisting of CD56, CD3 and CD19.

Abstract: The present invention discloses novel methods and compositions for identifying particular cell types in whole blood samples and defining either the concentration or ‘absolute count’ of these cells per unit volume of the sample. More specifically, the invention relates to methods for quantifying the antigen-specific T cells or defining the relative percentage of said cells in un-lysed whole blood. Further, the invention relates to kits for the preparation of whole blood samples for high-speed quantification of particular cell types, e.g. antigen specific T-cells, in said whole blood samples by flow cytometry.