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**Overview**: Natural Killer Cell Panel**Introduction**: The Natural Killer Cell Panel is a diagnostic tool designed to assess NK cell function using whole blood samples. In India, NK cell deficiencies contribute to recurrent viral infections, malignancy susceptibility, or primary immunodeficiencies (rare but severe), with low NK counts/activity in some chronic infections or post-chemotherapy. High morbidity from under-testing in rural/low-SES patients with recurrent herpesviruses or unexplained infections, limited flow cytometry labs, delayed IVIG or HSCT leading to fatal complications. Per immunology practices aligned with ICMR and Indian Society for Primary Immune Deficiency guidelines, the test employs flow cytometry for CD16, CD56, NK cell count, total lymphocytes, and NK activity over 1-2 days with high accuracy, valuable for evaluating innate immunity. This diagnostic falls under immune profiling and targets patients with recurrent infections or suspected PID, addressing accurate detection to guide supportive therapy or transplant. With elevated morbidity due to underdiagnosis, the test supports public health efforts by enabling precise NK cell assessment and reducing infection mortality. Its whole blood-based approach ensures reliable enumeration.**Other Names**: NK Cell Pnl.**FDA Status**: FDA approved, CLIA certified for hematology/immunology, compliant with 2025 standards.**Historical Milestone**: NK flow panel standard; in India, used in PID centers.**Purpose**: The test assesses 5 parameters including CD16 to guide NK cell function evaluation, assess innate immunity, inform therapy.**Test Parameters**: 1. CD16, 2. CD56, 3. NK Cell Count, 4. Total Lymphocytes, 5. NK Activity.**Pretest Condition**: No fasting required; patients should have recurrent infections.**Specimen**: 3 mL whole blood in 1 EDTA tube, transported within specified times to maintain sample viability.**Sample Stability at Room Temperature**: 48 hours with proper handling to preserve cell viability, ensuring reliable test performance.**Sample Stability at Refrigeration**: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.**Sample Stability at Frozen**: Not applicable (fresh sample preferred for flow).**Medical History**: Patients should provide details on infection pattern, malignancy.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of NK deficiency including recurrent infections, benefits of profiling, and minimal discomfort from blood draw.**Procedural Considerations**: The test involves sample processing using flow cytometry by trained personnel to ensure sterile technique, avoid hemolysis, and interpret results within 1-2 days using provided controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.**Factors Affecting Result Accuracy**: Delays beyond stability periods, improper storage conditions, or low lymphocyte count can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.**Clinical Significance**: Low NK count/activity indicates immunodeficiency, necessitating specialist input.**Specialist Consultation**: Immunologists should be consulted for management.**Additional Supporting Tests**: Functional NK assays for confirmation.**Test Limitations**: Requires viable cells; comprehensive approach required.**References**: Indian Journal of Pediatrics 2024, PID Studies India 2023. |
