Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Chronic Neutrophilic Leukemia ?
    ### Response:
    Chronic neutrophilic leukemia is a disease in which too many blood stem cells become a type of white blood cell called neutrophils. Neutrophils are infection -fighting blood cells that surround and destroy dead cells and foreign substances (such as bacteria).
    