AI-Assisted Fluorescence Microscopy of Leukocytes in Fresh Whole Blood

The goal of this observational study is to learn whether a microscope-based method with artificial intelligence (AI) can detect and classify white blood cells in fresh, unstained blood and measure the color of fluorescent light inside each cell, in healthy adult volunteers. The fluorescent dye is thought to reflect mitochondria (the parts of a cell that produce energy). The main questions it aims to answer are: 1. How accurately can the AI program detect white blood cells in fresh blood in the tile images? 2. Does the pattern of green, yellow, and red fluorescence inside individual white blood cells differ between dyes? Researchers will take microscope images of the same areas of each blood smear in regular light and in fluorescent light. The AI program outlines each white blood cell in the regular-light image, and a trained operator accepts, corrects, or rejects every outline. The accepted outlines are then used to measure the fluorescent colors in the same cells. As a reference, results are checked against standard stained blood smears (Romanowsky-Giemsa) read by laboratory staff. Participants will: Give a small blood sample by venipuncture (a needle in a vein of the arm) Repeat the blood draw about once a week for 3 to 6 weeks This study does not test any treatment, and participants will not receive any intervention.

Inclusion Criteria: * Healthy adult volunteers aged 18 to 65 years * Self-reported good health, confirmed by a screening questionnaire * Willing to give a venous blood sample about once a week for 3 to 6 weeks * Able to read and sign the informed consent form Exclusion Criteria: * Acute infection or fever within the last 14 days, or any symptoms of illness on the day of blood draw * Known blood disease (for example, anemia, leukemia, or a blood clotting disorder) or white blood cell count outside the laboratory reference range, if a complete blood count is available * Chronic inflammatory, autoimmune, metabolic (including diabetes), or cancer disease * Use in the last 30 days of corticosteroids, immunosuppressive or chemotherapy drugs, or growth factors that change white blood cell counts (for example, G-CSF) * Vaccination in the last 14 days * Pregnancy or breastfeeding * Blood donation or significant blood loss in the last 8 weeks * Intense physical exercise or alcohol use in the 24 hours before blood draw * Condition that makes venipuncture unsafe or unreasonable, as judged by the investigator