Leukocyte analysis: Current status and future direction

Leukocytes (white blood cells, WBCs) are a vital component of the human immune system, responsible for resisting foreign pathogens, repairing damaged tissues, and regulating immune responses. Abnormal changes in their number and function serve as clinical indicators of a wide range of diseases, including infection, inflammation, cancer, leukemia, and coronary artery disease. Precise analysis of their counts and functional status is invaluable for diagnosis, monitoring, and prognostic assessment. Leukocyte-testing equipment has become indispensable in modern clinical diagnostics; its significance lies not only in providing numerical read-outs but also in enabling data-driven decisions that guide therapy. These decisions directly affect patient survival rates, medical costs, and public health strategies. Leukocyte testing has progressed from an auxiliary diagnostic aid to a central element across the continuum of prediction, intervention, and individualized therapy, thereby continually advancing precision medicine. In this paper, we systematically review the evolution of leukocyte-detection technologies and compare the core principles, advantages, limitations, and application scenarios of both traditional and emerging methods. We further summarize and analyze the current bottlenecks that hinder clinical translation. Finally, we outline future directions for leukocyte detection, providing a valuable reference for its continued advancement and clinical adoption.