Patent ID: 8455209

Claim:
A reagent for analysis of immature leukocytes comprising: a polyoxyethylene nonionic surfactant which can damage cell membranes of erythrocytes and mature leukocytes, having the following formula (I): R 1 —R 2 —(CH 2 CH 2 O) n —H (I) wherein R 1 represents a C 9−25 alkyl, alkenyl or alkynyl group, R 2 represents —O—, —COO— or and n is an integer of 10 to 40, a solubilizing agent which can shrink the damaged blood cells and a dye for staining nucleic acid, wherein the reagent has an osmotic pressure of not lower than 10 mOsm/kg and lower than 150 mOsm/kg and the pH of the reagent is from greater than 5.0 up to 9.0.