(91 days)
Beckman Coulter's iTAg MHC Tetramer-CMV is for the identification and enumeration of cytomegalovirus (CMV) -specific CD8+ lymphocytes in whole blood by flow cytometry, and for the assessment of CMV-specific immune status in immunosuppressed stem cell transplant recipients. The assay is limited to individuals with the following HLA types: A0101, A0201, B0702, B0801, B*3501.
iTAg™ MHC Tetramer CMV is similar to existing CD (cluster differentiation) technology, measuring subsets of an individual's total leukocyte population. The tetramer kits include five tetramers specific for particular CD3+CD8+ cell receptors. While 5 alleles are provided for this assay, an individual's analysis may use up to 4 of these 5 tetramers. Tetramers enumerate CD3+CD8+ subsets by flow cytometry, similar to antibodies: Same specimen (whole blood), indication (identification and enumeration of lymphocyte populations), platform (flow cytometry), fluorochromes, Flow-Count Fluorospheres, and accessory reagents. The assay components include: Vials of anti-CD8 FITC, Vials of anti-CD4 PE, Vials of anti-CD3 PC5, Vials of Flow-Count Beads, Vials of lysing agent, Vials of fixative, Up to 5 vials of individual Tetramers labeled with PE, Vials of negative Tetramer labeled with PE.
Here's a breakdown of the acceptance criteria and study information for the iTAg MHC Tetramer-CMV device, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance:
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Specificity | No significant interference from common interferents. | No significant interference from common interferents (Monocytes, granulocytes, platelets, red blood cells). No significant interference from similar viral response (EBV). Tetramers were specific for identified alleles. |
| Linear Range | Acceptable correlation between expected and actual values. | Deming regression analysis showed acceptable correlation. Upper limit varied by allele (119 to >300 cells/µL). |
| Accuracy and Recovery | Acceptable recovery for cells/µL and % tetramer positive. | All tetramers demonstrated acceptable recovery. Overall percent recovery across three tetramers was 96%. |
| Analytical Sensitivity | Defined lower limit of detection. | 1.0 cell/µL for absolute counts. 0.2% tetramer positive. |
| Reproducibility | Acceptable CV ranges for intra- and inter-laboratory testing. | Intra-laboratory: 1.3% CV to 16.3% CV. |
| Inter-laboratory (Beckman Coulter facilities): 0.9% CV to 13.3% CV. | ||
| Inter-laboratory (Beckman Coulter + two external sites): 2.6% CV to 29.6% CV. | ||
| Instrument Comparison | Comparable results and interchangeability between specified flow cytometers; acceptable correlation. | BD FACSCalibur vs. BCI EPICS-XL (Absolute Counts): Comparable results, interchangeable. Deming regression: y = 0.9697x - 0.3255, r = 0.9978. |
| BD FACSCalibur vs. BCI EPICS-XL (% Tetramer Positive): Comparable results, interchangeable. Deming regression: y = 0.9800x - 0.0152, r = 0.9982. | ||
| BCI FC500 vs. BCI EPICS-XL (Absolute Counts): Comparable results, interchangeable. Deming regression: y = 0.9812X + 0.1527, r = 0.9921. | ||
| BCI FC500 vs. BCI EPICS-XL (% Tetramer Positive): Comparable results, interchangeable. Deming regression: y = 1.0426X - 0.0448, r = 0.995. | ||
| Imprecision (Absolute Counts): Comparable between instruments, averaged |
§ 864.5220 Automated differential cell counter.
(a)
Identification. An automated differential cell counter is a device used to identify one or more of the formed elements of the blood. The device may also have the capability to flag, count, or classify immature or abnormal hematopoietic cells of the blood, bone marrow, or other body fluids. These devices may combine an electronic particle counting method, optical method, or a flow cytometric method utilizing monoclonal CD (cluster designation) markers. The device includes accessory CD markers.(b)
Classification. Class II (special controls). The special control for this device is the FDA document entitled “Class II Special Controls Guidance Document: Premarket Notifications for Automated Differential Cell Counters for Immature or Abnormal Blood Cells; Final Guidance for Industry and FDA.”