Novel method of testing myelotoxicity with the use of flow cytometer

The subjects of the present invention are to solve low test efficiency and low accuracy which are problems encountering in the conventional methods for testing myelotoxicity by observing smears. To solve the subjects, the inventors of the present invention consider that it is initially necessary to clarify markers for discriminating and identifying hematopoietic stem cells and blood cells at various differentiation stages in bone marrow. From this point of view, cell surface antigens are specified. Thus, it is found that the myelotoxicity of a drug can be evaluated with a high efficiency at a high accuracy by analyzing the quantity of expression of these antigens with the use of a flow cytometer.