Abstract: The present invention provides an improved reagent composition and method to perform white blood cell differential counting and subpopulation analysis using both fresh and aged blood samples with accuracy and precision. The invention is particularly applicable for the analysis of aged blood samples that have been stored at room temperature for over a day, thereby allowing accurate and useful information to be obtained from samples that are normally considered to be suboptimal. The improved reagent composition and method are particularly related to the peroxidase method of white blood cell differential determinations. One aspect of the invention includes an improved aqueous reagent composition for carrying out the peroxidase method of differential counting.

Abstract: A method is disclosed for differentiating white blood cells. The method uses at least one surfactant and at least one dilute acid which together selectively strip the cytoplasm from certain classes of white blood cells and not others. More particularly, the method causes lysis of lymphocytes, monocytes, eosinophils and neutrophils, but not basophils. Thus, basophils are differentiated from other PMN sub-classes by their appearance as intact cells. The method totally avoids the need for dye preparation and the vagaries of staining techniques and can be used either manually or with instrumentation.

Abstract: This invention relates to a method for the rapid determination of a differential white blood cell count in a sample, which method comprises:(a) preparing a reagent solution comprisingformaldehyde or paraformaldehyde;a surfactant;a sugar or sugar alcohol; anda buffer; and(b) rapidly mixing the reagent solution with the sample to be analyzed to form a reaction mixture, wherein both the reagent solution and the sample are initially at room temperature; and(c) rapidly heating the reaction mixture to a temperature of from about 62.degree. C. to about 72.degree. C. in order to lyse the red blood cells in the sample and fix the white blood cells in said sample. The invention also relates to the reagent solution of part (a) of the method.

Abstract: This invention relates to a method for the rapid determination of a differential white blood cell count in a sample, which method comprises:(a) preparing a reagent solution comprising;formaldehyde or paraformaldehyde;a surfactant;a sugar or sugar alcohol; anda buffer; and(b) rapidly mixing the reagent solution with the sample to be analyzed to form a reaction mixture, wherein both the reagent solution and the sample are initially at room temperature; and(c) rapidly heating the reaction mixture to a temperature of from about 62.degree. C. to about 72.degree. C. in order to lyse the red blood cells in the sample and fix the white blood cells in the sample.