Final answer:
Flow cytometry, especially when paired with Fluorescence-Activated Cell Sorting (FACS), is a versatile tool used in clinical practice and research for characterizing, counting, and sorting different cell types, as well as diagnosing abnormal cell profiles and blood cancers.
Step-by-step explanation:
Flow cytometry or Fluorescence-Activated Cell Sorting (FACS) is a biotechnological technique that can characterize, count, and sort different blood cell types, among other applications. Fluorescently conjugated monoclonal antibodies (mAbs) against cell membrane proteins enable the detection of specific cell subsets. Cells tagged with these antibodies pass through a narrow capillary in a flow cytometer and are excited by a laser, allowing for their fluorescence to be detected and analyzed. Consequently, flow cytometry can be used to diagnose abnormal blood cell profiles or blood cancer subtypes by identifying quantities of cells such as CD4 T cells, which are crucial for assessing the immune status of patients with HIV. However, flow cytometry is not typically used for determining serum albumin levels, blood cholesterol, urea levels, or kidney filtration rates, as these assessments are achieved through different biochemical assays.