For in vitro diagnostic use to identify and enumerate percentages and absolute counts of CD3+ and CD3+CD8+ lymphocytes in blood.
Device Story
System uses three-color monoclonal antibody reagents (CD3 FITC/CD8 PE/CD45 PerCP) to label specific leukocyte antigens in whole blood. Samples are processed via erythrocyte lysis and analyzed on a flow cytometer. For absolute counts, TRUCOUNT tubes containing a known quantity of beads are used. Device identifies lymphocyte subsets using fluorescence gating on CD45+ populations rather than forward scatter. Output includes percentage and absolute count (cells/μL) of T-lymphocytes (CD3+) and T-suppressor/cytotoxic cells (CD3+CD8+). Used in clinical laboratories by trained personnel to monitor disease progression and immune status. Results assist clinicians in managing autoimmune conditions and immunodeficiencies.
Clinical Evidence
Multi-site clinical studies (Cleveland Clinic, Johns Hopkins, etc.) compared TriTEST/TRUCOUNT to predicate devices. Accuracy demonstrated equivalence. Stability studies established sample handling protocols (staining/analysis timeframes). Linearity confirmed across 200–16,700 lymphocytes/μL. Reproducibility was acceptable. Cross-platform study showed good correlation with non-BD flow cytometers, though users are advised to validate performance.
Technological Characteristics
Three-color immunofluorescence reagent (FITC, PE, PerCP conjugates). Uses flow cytometry (488 nm laser excitation). Includes TRUCOUNT tubes with internal bead standards for absolute quantification. Employs fluorescence-based gating on CD45+ populations. Compatible with standard flow cytometers meeting specific spectral detection requirements.
Indications for Use
Indicated for use with flow cytometers (488 nm laser; detection at 515-545 nm, 562-607 nm, >650 nm) and erythrocyte-lysed whole blood. Used to characterize and monitor autoimmune diseases (e.g., lupus) and congenital or acquired immunodeficiencies (e.g., SCID, AIDS).
Regulatory Classification
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.
Special Controls
*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.”
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BDIS RA
005
K970326
NOV 21 1997
# Attachment B
## Summary of Safety and Effectiveness
**Submitter Information (21 CFR 807.92(a)(1))**
**Submitter:** Becton Dickinson Immunocytometry Systems
2350 Qume Drive
San Jose, CA 95131-1807
**Contact:** Anna Longwell, Esq.
Director, Regulatory Affairs - Corporate
(408) 954-2254
**Summary date:** November 19, 1997
**Name of Device and Classification (21 CFR 807.92(a)(2))**
**Name:** Becton Dickinson TriTEST™ reagent CD3 FITC/CD8 PE/CD45 PerCP; TRUCOUNT™ Absolute Count Tubes
**Classification:** Class II
**Predicate Device (21 CFR 807.92(a)(3))**
The BDIS TriTEST™ CD3 FITC/CD8 PE/CD45 PerCP reagent, when used to enumerate percentages of lymphocytes is substantially equivalent to IMK-Lymphocyte Tube E that was cleared to market under 510(k) K913192. When the TriTEST reagent is used with TRUCOUNT Absolute Count Tubes, it is substantially equivalent to the BDIS FACSCount system cleared under 510(k) K933486.
**Description of the Device (21 CFR 807.92(a)(4))**
The BDIS TriTEST CD3 fluorescein isothiocyanate (FITC)/CD8 phycoerythrin (PE)/CD45 peridinin chlorophyll protein (PerCP) reagent is a three-color, direct immunofluorescence reagent for identifying and enumerating percentages of T lymphocytes (CD3+) and T-suppressor/cytotoxic (CD3+CD8+) cells in erythrocyte-lysed whole blood (LWB). When used with TRUCOUNT Absolute Count Tubes, the product will yield absolute counts in cells/μL. The Becton Dickinson TriTEST/TRUCOUNT system for immunophenotyping consists of a flow cytometer (either from BDIS or from another manufacturer), conjugated monoclonal reagent (TriTEST CD3 FITC/CD8 PE/CD45 PerCP) 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
CD3/CD8/CD45 510(k) Notification
Attachment B: Summary of Safety and Effectiveness
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# Summary of Safety and Effectiveness
ratio of reagent-positive events 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 bead events (P) is computed. The absolute count is P x (beads/pellet)/(volume of blood sample).
When monoclonal antibody reagents are added to human whole blood, the fluorochrome-labeled antibodies bind specifically to antigens on the surface of leukocytes, thus identifying lymphocyte populations. The patient blood sample is added to the counting bead pellet 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.
## Intended Use (21 CFR 807.92(a)(5))
For in vitro diagnostic use to identify and enumerate percentages and absolute counts of CD3+ and CD3+CD8+ lymphocytes in blood.
## Indications for Use
- For use with any flow cytometer equipped with a 488 nm laser and capable of detection in the ranges: 515-545 nm, 562-607 nm, and >650 nm
- For use with erythrocyte lysed whole blood
- For use with or without an isotype control
- To characterize and monitor forms of autoimmune diseases, such as lupus
- To characterize and monitor congenital or acquired immunodeficiencies, such as SCID or AIDS
CD3/CD8/CD45/TRUCOUNT 510(k) Notification
Attachment B: Summary of Safety and Effectiveness
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# Summary of Safety and Effectiveness
## Clinical Utility
The determination of CD3+ and CD3+CD8+ lymphocytes has been found useful in monitoring some forms of immunodeficiency and autoimmune disease.
## Comparison to Predicate Device (21 CFR 807.92(a)(6))
The CD3 FITC/CD8 PE/CD45 PerCP TriTEST reagent, when used to enumerate percentages of lymphocytes, is substantially equivalent to the IMK-Lymphocyte Tube E that was cleared to market under 510(k) K913192. When used with TRUCOUNT Absolute Count Tubes to enumerate absolute counts, it is substantially equivalent to the FACSCount System (K933486) for CD3+ and CD3+CD8+. Both the TriTEST product and the predicate devices yield equivalent results for the same analytes, and both are intended for use as an in vitro diagnostic test using a flow cytometer-based instrument and recommended computer hardware and software. The products differ in the steps used to determine analysis gates to identify the lymphocyte population.
## Performance Data (21 CFR 807.92(b)(2))
Performance of the product was established by testing at Cleveland Clinic, Johns Hopkins Hospital, Institute of Tropical Medicine, University of North Carolina, and at Becton Dickinson Immunocytometry Systems laboratories in San Jose, California.
Several studies were performed:
- Accuracy was determined by comparison to both IMK-Lymphocyte Tube E and the FACSCount system. Accuracy data demonstrated the TriTEST and TriTEST/TRUCOUNT product's equivalence to IMK-Lymphocyte Tube E and FACSCount, respectively.
- Use of isotype control was studied. Data were analyzed for percent CD3+ and percent CD3+CD8+ first using a control to set gates and markers and then using only the stained sample to set gates and quadrant markers. Data indicated that the reagent may be used with or without an isotype control.
- Reference range studies were performed. Many variables, such as sex, age and geographical location may influence the reference range. Each site must determine its own reference range.
- A stability study was conducted to assess the time effect relating to age of blood (time-from-draw) and the time effect relating to the age of the stain (time-from-sample preparation), as well as the
CD3/CD8/CD45/TRUCOUNT 510(k) Notification
Attachment B: Summary of Safety and Effectiveness
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# Summary of Safety and Effectiveness
combined effect of both. Stability was determined for both percentages and absolute counts. Stability was determined for whole blood samples at 6, 24, 48 and 72 hours post draw. Additionally, stability was measured for stained samples at 6 and 24 hours from time of staining. A combination of the two, time from draw plus time from sample preparation, was studied. Results indicated that either 1) staining the samples within 24 hours of draw and analyzing samples within 24 hours of staining or alternatively, 2) staining the samples with 48 hours of draw and analyzing them within 6 hours is recommended.
- **Within-specimen reproducibility** was performed at BDIS and at three clinical sites for both percentage enumeration and absolute counts. Results demonstrated acceptable within-sample reproducibility.
- **Linearity** was determined using blood samples from three normal donors diluted to five concentrations, ranging from 16,700 to 200 lymphocytes/μL and from 31,000 to 2,500 WBC/μL. Results indicate the product gives linear results over this range.
- **Cross reactivity** of these clones is reported in the literature. Conjugation and product formulation have not changed their specificity.
- Results from a **cross platform reproducibility** study indicated 1) for absolute count results there was a small (< 20%) non-zero bias, but good correlation between results on a Becton Dickinson flow cytometer versus a Coulter cytometer. Therefore, users will be advised that they must validate performance characteristics for absolute counts. 2) For determining percent positive results or absolute counts, TriTEST reagent with TRUCOUNT Absolute Count Tube may be used with flow cytometers not made by Becton Dickinson.
## Performance Data - Conclusions (21 CFR 807.92(b)(3))
The results of the clinical studies demonstrate that the device is as safe and effective as the predicate devices.
CD3/CD8/CD45/TRUCOUNT 510(b) Notification
Attachment B: Summary of Safety and Effectiveness
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DEPARTMENT OF HEALTH & HUMAN SERVICES
Public Health Service
Food and Drug Administration
2098 Gaither Road
Rockville MD 20850
Ms. Anna Longwell, Esq.
Director, Regulatory Affairs - Corporate
Becton Dickinson Immunocytometry Systems
2350 Qume Drive
San Jose, California 95131-1807
NoV 21 1997
Re: K970326
Trade Name: Becton Dickinson TriTEST™ Reagent CD3 FITC/CD8 PE/CD45 PerCP; TRUCOUNT™ Absolute Count Tubes
Regulatory Class: II
Product Code: GKZ
Dated: August 28, 1997
Received: September 2, 1997
Dear Ms. Longwell:
We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the current Good Manufacturing Practice requirement, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic (QS) inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal Laws or Regulations.
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Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88), this device may require a CLIA complexity categorization. To determine if it does, you should contact the Centers for Disease Control and Prevention (CDC) at (770)488-7655.
This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for *in vitro* diagnostic devices), please contact the Office of Compliance at (301) 594-4588. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll free number (800) 638-2041 or at (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html"
Sincerely yours,
Steven I. Gutman, M.D., M.B.A.
Director
Division of Clinical Laboratory Devices
Office of Device Evaluation
Center for Devices and Radiological Health
Enclosure
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Attachment A
TriTEST CD3/CD8/CD45 with TRUCOUNT Control Beads & Absolute Count Tubes K970326
# Indications for Use Statement
- For use with any flow cytometer equipped with a 488 nm laser and capable of detection in the ranges: 515-545 nm, 562-607 nm, and > 650 nm
- For use with erythrocyte lysed whole blood
- For use with or without an isotype control
- To characterize and monitor forms of autoimmune diseases, such as lupus
- To characterize and monitor congenital or acquired immunodeficiencies, such as SCID or AIDS
(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED)
Concurrence of CDRH, Office of Device Evaluation (ODE)

Prescription Use
(Per 21 CFR 801.109)
OR
Over-The-Counter Use
(Optional Format 1-2-96)
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Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
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With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.