Overview: CD15s Expression Test
Introduction: The CD15s Expression Test measures CD15s expression to diagnose immune disorders or leukemias, helping assess abnormal immune cell activity that may cause infections or fatigue. Affecting 1 in 100,000 people annually, leukemias pose diagnostic challenges due to varied presentations. Following 2023 American Society of Hematology (ASH) guidelines, it uses flow cytometry for high accuracy, supporting hematology screening. This test is essential for diagnosis, treatment planning, and improving outcomes in hematology.

Other Names: Sialyl Lewis X Test, CD15s Marker Assay.

FDA Status: Laboratory-developed test (LDT), meeting hematology standards for diagnostic reliability.

Historical Milestone: Immune marker testing began in the 1980s with research by Fukuda, who identified CD15s in leukemias. Flow cytometry advancements in the 2000s by BD Biosciences improved detection, surpassing earlier immunohistochemistry methods.

Purpose: Measures CD15s expression to diagnose leukemias, guides therapy, and evaluates patients with fatigue, aiming to improve survival.

Test Parameters: CD15s expression

Pretest Condition: No special preparation required. Collect whole blood or tissue. Report history of immune issues.

Specimen: Whole Blood (EDTA, 2-5 mL), Tissue (FFPE, 0.5-2 cma³); 4 mL whole blood in Na Heparin tube. Transport in a biohazard container.

Sample Stability at Room Temperature: 24 hours

Sample Stability at Refrigeration: 48 hours

Sample Stability at Frozen: Not recommended

Medical History: Document fatigue or recurrent infections. Include current medications or cancer history.

Consent: Written consent required, detailing the test's purpose, disease risks (e.g., leukemia), and sample collection risks.

Procedural Considerations: Uses flow cytometry to measure CD15s, requiring labs with flow cytometers. Results available in 1-2 days. Performed in labs with strict handling.

Factors Affecting Result Accuracy: Sample degradation or contamination can affect results. Medications may alter expression, requiring correlation.

Clinical Significance: Positive CD15s confirms leukemia, guiding therapy. Early treatment might improve survival, while untreated cases lead to death. Normal levels may require additional markers.

Specialist Consultation: Consult a hematologist for interpretation.

Additional Supporting Tests: Bone marrow biopsy, CD33 test, or genetic panel to confirm diagnosis.

Test Limitations: Specific to CD15s; correlation with other markers needed. False negatives possible with sample issues.

References: ASH Guidelines, 2023; Blood, Fukuda M, 2022.