CPT® Code 86344

Leukocyte phagocytosis is a critical immunological process involving the body's white blood cells, known as leukocytes, which play a vital role in the immune response. These cells are produced and stored in lymphoid organs, such as the spleen and lymph nodes, as well as in various tissues throughout the body. Once produced, leukocytes circulate through the lymphatic system and bloodstream, where they are tasked with identifying and eliminating invading pathogens, including bacteria and viruses. Among the different types of leukocytes, neutrophils are particularly significant as they are specialized in targeting and destroying bacteria. The leukocyte phagocytosis test quantitatively assesses the ability of neutrophils to ingest bacteria, providing valuable insights into the immune system's functionality. This test measures the percentage of neutrophils that have successfully ingested bacteria and counts the number of bacteria per cell. To perform this test, a whole blood sample is collected and incubated with labeled Escherichia coli (E. coli) bacteria. The phagocytosis process is then halted by adding a quenching solution, which differentiates between bacteria that are merely attached to the cell surface and those that have been internalized. This is achieved by quenching the fluorescence of surface-bound bacteria while preserving the fluorescence of those that have been ingested. Following this, a lysing solution is introduced to eliminate red blood cells and fix the leukocytes for analysis. The sample undergoes washing, and a DNA staining solution is applied to exclude non-target aggregates. Finally, flow cytometry is utilized to analyze the sample, allowing for precise quantification of the phagocytic activity of neutrophils.