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Official Description

Leukocyte phagocytosis

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

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.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The leukocyte phagocytosis test is indicated for various clinical scenarios where the assessment of immune function is necessary. This includes:

  • Infection Evaluation This test is performed to evaluate the immune response in patients suspected of having infections, particularly those caused by bacteria.
  • Immunodeficiency Assessment It is used to assess patients with suspected immunodeficiency disorders, where the ability of leukocytes to respond to pathogens may be compromised.
  • Monitoring Treatment Efficacy The test can be utilized to monitor the effectiveness of treatments aimed at enhancing immune function or addressing infections.

2. Procedure

The leukocyte phagocytosis test involves several detailed procedural steps to ensure accurate measurement of neutrophil activity. These steps include:

  • Step 1: Sample Collection A whole blood sample is collected from the patient, which serves as the basis for the phagocytosis test.
  • Step 2: Incubation with Bacteria The collected blood sample is then incubated with labeled E. coli bacteria. This step allows the neutrophils present in the blood to interact with the bacteria, initiating the phagocytosis process.
  • Step 3: Quenching the Phagocytosis Process After incubation, a quenching solution is added to halt the phagocytosis process. This solution is crucial as it differentiates between bacteria that are merely attached to the surface of the neutrophils and those that have been internalized.
  • Step 4: Lysing Red Blood Cells A lysing solution is introduced to remove red blood cells from the sample. This step is essential to isolate the leukocytes for further analysis.
  • Step 5: Fixation of Leukocytes The lysing solution also serves to fix the leukocytes, preserving their state for accurate analysis.
  • Step 6: Washing the Sample The sample is then washed to eliminate any remaining debris and prepare it for the next step.
  • Step 7: DNA Staining A DNA staining solution is added to the sample. This solution helps to exclude non-target aggregates, ensuring that only the relevant leukocytes are analyzed.
  • Step 8: Flow Cytometry Analysis Finally, flow cytometry is performed on the prepared sample. This advanced technique allows for the precise quantification of the phagocytic activity of neutrophils by analyzing the fluorescence of internalized bacteria.

3. Post-Procedure

After the leukocyte phagocytosis test is completed, there are no specific post-procedure care requirements mentioned. However, it is essential for healthcare providers to monitor the patient for any potential adverse reactions related to the blood draw. The results of the test will be analyzed and interpreted by qualified professionals, who will then discuss the findings with the patient and determine any necessary follow-up actions based on the results.

Short Descr LEUKOCYTE PHAGOCYTOSIS
Medium Descr LEUKOCYTE PHAGOCYTOSIS
Long Descr Leukocyte phagocytosis
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
CCS Clinical Classification 235 - Other Laboratory
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
Q4 Service for ordering/referring physician qualifies as a service exemption
Date
Action
Notes
Pre-1990 Added Code added.
Code
Description
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