The leukocyte reading protocol on the flow cytometer is a standardized method used to analyze different subtypes of leukocytes (white blood cells) within a blood sample. Using flow cytometry, the protocol involves staining leukocytes with specific fluorochrome-labeled antibodies that target cell surface markers unique to various leukocyte subtypes. The sample is then passed through the flow cytometer, where light scattering and fluorescence are measured to identify and quantify the different leukocyte populations, including lymphocytes, monocytes, and granulocytes. This method provides detailed information on the relative distribution and activation states of leukocytes, which is crucial for diagnosing and monitoring immune-related diseases, infections, and blood disorders.