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For in vitro diagnostic use to identify and enumerate percentages and absolute counts of T and B lymphocytes in bload.

Indications for Use

• For use with any flow cytometer with specified detection ranges .
• For use with erythrocyte lysed whole blood .
• For use with or without an isotype control .
• For in vitro diagnostic use .
• To identify and enumerate percentages and absolute counts of CD3+ and CD19+ ● lymphocytes
• To characterize and monitor some forms of immunodeficiency .
• To characterize and monitor some forms of autoimmune diseases .

The BDIS TriTEST CD3 fluorescein isothiocyanate (FITC)/CD19 phycoerythrin (PE)/CD45 peridinin chlorophyll protein (PeCP) reagent is a three-color, direct immunofluorescence reagent for identifying and enumerating percentages of T lymphocytes (CD3+) and B lymphocytes (CD19+) in eythrocyte-lysed whole blood (LWB). When used with TRUCOUNT Absolute Count Tubes, the product will yield absolute counts in cells/uL. The Becton Dickinson Tril EST / TRUCOUNT system for immunophenotyping consists of a flow cytometer (cither from BDIS or from another manufacturer), conjugated monoclonal reagent (TriTEST CD3 FITC/CD19 PE/CD45 PeCP) and TRUCOUNT Absolute Count Tubes.

The process to obtain lymphocyte subset percentages includes: 1) obtaining a whole blood sample, 2) cell-surface antigen staining with three-color monoclonal antibody reagents, 3) erythrocyte lysis, and 4) flow cytometric acquisition and analysis of list mode data. Analysis involves computing the ratio of reagent-positive events (CD3+ and CD19+) to the CD45 positive events, and expressing the ratio as a percentage.

To obtain absolute counts, the TriTEST reagent and whole blood are added directly to an Absolute Count Tube prior to lysis. The remaining process, until analysis, is identical to that for percentages. Analysis for absolute counts requires that an additional region, the bead region, be identified and the events in this region counted. The proportion of reagent positive events to be identified and are trated. The absolute count is P x (beads/pellet)/(volume of blood sample).

When monoclonal antibody reagents are added to human whole blood, the fluorochromelabeled antibodies bind specifically to antigens on the surface of leucocytes, thus identifying lymphocyte populations. The patient blood sample is added to the counting bead peller and is treated with fluorochrome-labeled antibodies and the erythrocytes are lysed with FACS® Lysing Solution. The flow cytometer is set up so that cell populations for most samples occupy approximately the same region of fluorescence space. The sample is then introduced into the flow cytometer and the stained cells and beads fluoresce when excited by a laser beam.

The three-color reagent permits identification of lymphocyte subsets using fluorescence gating instead of forward scatter gating. This three-color reagent allows direct gating on the CD45-positive population using a combination of fluorescence and side scatter parameters. By gating on the CD45-positive population, a maximum number of lymphocytes may be captured in the gate and non-lymphocyte contamination may be minimized.

The Becton Dickinson TriTEST reagent CD3 FITC/CD19 PE/CD45 PerCP with TRUCOUNT Absolute Count Tubes received 510(k) clearance (K970742) in 1997. The device is intended for in vitro diagnostic use to identify and enumerate percentages and absolute counts of T and B lymphocytes in erythrocyte-lysed whole blood, and to characterize and monitor some forms of immunodeficiency and autoimmune diseases.

Here's a breakdown of the acceptance criteria and study information:

1. Acceptance Criteria and Reported Device Performance

2. Sample Size Used for the Test Set and Data Provenance

• Accuracy: Not explicitly stated for accuracy comparison, but implies a sufficient number of samples were tested to demonstrate equivalence.
• Isotype Control: Sample size not explicitly stated.
• Reproducibility (Within-specimen):
  • BDIS Internal Study: 3 samples (1 high, 1 medium, 1 low concentration of T and B lymphocytes), with 10 replicates each.
  • Clinical Site Study: 92 donors for CD3+ and 80 donors for CD19+, with 3 aliquots assessed from each donor.
• Linearity: Blood samples from 3 normal donors.
• Data Provenance: Studies were performed at Cleveland Clinic, Johns Hopkins Hospital, Institute for Medical Research at the University of North Carolina, and at Becton Dickinson Immunocytometry Systems laboratories in San Jose, California. This indicates a mix of external clinical sites and internal company labs, suggesting prospective data collection for these specific studies.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications

The provided text does not specify the number or qualifications of experts used to establish the ground truth for the test set. Given the nature of the device (flow cytometry for lymphocyte enumeration), the ground truth would likely be established through comparisons with established methods and/or expert review of flow cytometry plots.

4. Adjudication Method for the Test Set

The provided text does not specify any explicit adjudication method (e.g., 2+1, 3+1, none) for the test set.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

An MRMC study was not done. The device's performance was compared to a predicate device (Simultest™ IMK-Lymphocyte Tube C plus ADCC and the hematology analyzer) and internal reproducibility studies, not through a study involving multiple human readers with and without AI assistance to measure improvement in human performance.

6. Standalone (Algorithm Only) Performance

This device is a reagent and tube system for use with a flow cytometer. Its performance is intrinsically linked to the overall system (reagent, sample preparation, flow cytometer, and analysis software). Therefore, a "standalone algorithm only" performance study in the sense of a pure AI algorithm is not applicable to this type of medical device. The performance data presented (accuracy, reproducibility, linearity, etc.) inherently reflect the "algorithm only" performance within the context of the complete TriTEST/TRUCOUNT system.

7. Type of Ground Truth Used

The primary ground truth used for the performance studies appears to be:

• Comparison to Predicate Device: For accuracy, the device was compared against the established Simultest™ IMK-Lymphocyte Tube C plus ADCC. This implies that the predicate device's results serve as a form of "ground truth" for demonstrating equivalence.
• Internal Consistency/Expected Biological Ranges: For reproducibility, stability, and linearity, the ground truth is based on the expectation of consistent results from the same sample or linear responses over dilution ranges, consistent with established biological principles and laboratory practices.

8. Sample Size for the Training Set

The document does not specify a separate "training set" sample size. For in vitro diagnostic reagents and systems like this, the development process (which might involve data analogous to a training set) is not typically detailed in terms of sample size in a 510(k) summary. The performance data presented are from validation studies, which are akin to testing.

9. How the Ground Truth for the Training Set Was Established

As no explicit "training set" is mentioned for an AI/algorithm-based device, information on how its ground truth was established is not applicable in this context. The product is a diagnostic reagent and counting tube system, not a machine learning algorithm that requires a labeled training dataset in the modern sense.

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