The Dry Tri T-STAT (CD3/CD4/CD8) reagent, intended for in vitro diagnostic use, is a three color immunofluorescence stain for the labeling, identification, and enumeration of helper/inducer (CD3+CD4+) and cytotoxic/suppressor (CD3+CD8+) T lymphocytes combined with a precise number of fluorescent counting beads to provide absolute CD4+ and CD8+ T-Cell counts on a single platform. This reagent is intended to be used for flow cytometric analysis of erythrocyte-lysed human whole blood. The Tri T-STAT Reagent can be used to monitor forms of immunodeficiency.

Device Description

The Dry Tri T-STAT (CD3/CD4/CD8) reagent contains Atto488 - labeled CD4 monoclonal antibody (clone RPA-T4); phycoerythrin(PE) - labeled CD8 monoclonal antibody (clone LT8); and PE = Dyomics649 - labeled CD3 monoclonal antibody (clone UCHT1) formulated with fluorescent counting beads and stabilizers. The conjugated antibodies and beads are dispensed into flow cytometer compatible plastic tubes and dried. The material in each tube is used to process a single sample. The Dry Tri T-STAT (CD3/CD4/CD8) reagent, three color immunofluorescence stain, labels, identifies, and enumerates helper/inducer (CD3+CD4+) and cytotoxic/suppressor (CD3+CD8+) T lymphocytes. Combined with a precise number of fluorescent counting beads, in each tube, the reagent provides absolute CD4+ and CD8+ T-Cell counts on a single platform.

AI/ML Overview

The provided text describes the performance characteristics of the Dry Tri T-STAT (CD3/CD4/CD8) reagent, a device for enumerating T lymphocytes.

Here's a breakdown of the requested information based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria / Performance Characteristic	Reported Device Performance
Precision/Reproducibility	Acceptable. Average %CV better than 10% for high, medium, and low count samples (10 replicates within run).
Linearity (CD4+ T-cells)	Acceptable. Correlation coefficient > 0.99 over reportable range (65-1500 cells/ul).
Linearity (CD8+ T-cells)	Acceptable. Correlation coefficient > 0.99 over reportable range (50-1500 cells/ul).
Sample Stability (24 hours post-draw)	Acceptable for absolute CD4+ and CD8+ T-cell concentrations.
Sample Stability (7 days, processed at phlebotomy)	Acceptable for absolute CD4+ and CD8+ T-cell concentrations.
Cross-reactivity	Monoclonal antibodies' specificities (established at International Workshops on Human Leukocyte Differentiation Antigens) were maintained after conjugation.
Correlation to Predicate Devices (CD4+ T-cell counts)	R² = 0.99, 0.93, 0.91, & 0.99 when compared at four different sites.
Correlation to Predicate Devices (CD8+ T-cell counts)	R² = 0.96, 0.91, & 0.96 when compared at four different sites.

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

Sample Size: 291 samples were used for the correlation study against predicate devices.
Data Provenance: The correlation study was conducted at "four different sites." The country of origin is not explicitly stated, but the submission is to the US FDA, implying relevance to a US context or similar regulatory standards. The study appears to be retrospective in the sense that the predicate devices are already established, and these samples were analyzed using both the new device and predicate devices. However, the exact nature (e.g., archived samples vs. newly collected for the study) is not specified.

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

This information is not provided in the document. The ground truth for the correlation study appears to be the results obtained from the predicate devices, not an expert-established ground truth.

4. Adjudication Method for the Test Set

This information is not applicable and therefore not provided. The study design directly compares the new device's output to that of predicate devices; there is no indication of an independent adjudication process for discrepancies.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

This information is not applicable and therefore not provided. The device is a diagnostic reagent for flow cytometric analysis, not an AI-assisted diagnostic tool that involves human readers.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done

Yes, the performance characteristics described (precision, linearity, sample stability, cross-reactivity, and correlation to predicate devices) represent the standalone performance of the Dry Tri T-STAT reagent. There is no mention of human input or "human-in-the-loop" influencing its measurement outputs once samples are processed according to the "no wash" protocol.

7. The Type of Ground Truth Used

For the correlation study, the "ground truth" was established by comparison to predicate devices. For other performance characteristics (precision, linearity, stability), the ground truth is implicitly based on established analytical standards and measurements within an accredited lab setting, rather than expert consensus, pathology, or outcomes data.

8. The Sample Size for the Training Set

This information is not provided and is not applicable as this device is a reagent for laboratory testing and not an AI/machine learning algorithm requiring a "training set" in the computational sense.

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

This information is not provided and is not applicable as the device is a reagent and does not involve a training set.

Summary

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K08209/

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510(k) Summary

APR 1 5 2009

Submitter information

Submitter:	Reametrix, Inc.1585 Industrial RoadSan Carlos, CA 94070Phone: (650)620-9253	Fax: (650)620-0093
Contact:	Steven KunitakeDirector(650)620-9253 x104

December 5, 2008 Summary preparation date:

Device names and classification

Trade name:	Dry Tri T-STAT (CD3/CD4/CD8) reagent
Common name:	CD3-PE-D649/CD4-A488/CD8-PE reagent with fluorescentcounting beads
Device classification:	The Dry Tri T-STAT (CD3/CD4/CD8) reagent is a Class II device(21 CFR 864.5220, Panel code: GKZ)

Predicate devices

Becton Dickinson TriTESTTM reagent CD4 FITC/CD8 PE /CD3 PerCP; TruCOUNTTM Absolute counting tubes (K971205) Beckman Coulter CYTO-STAT® CD45-FITC/CD4-PE/CD8-ECD/CD3-PC5 tetraCHROME™ (K030408)

Device Description

1585 Industrial Road, San Carlos, CA 94070-4130 Tel: (650) 620-9253 Fax: (650) 620-0093

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Intended Use

The Dry Tri T-STAT (CD3/CD4/CD8) reagent is a three color immuno-fluorescence stain for the labeling, identification, and enumeration of helper/inducer (CD3+CD4+) and cytotoxic/suppressor (CD3+CD8+) T lymphocytes combined with a precise number of fluorescent counting beads for absolute CD4+ and CD8+ T-Cell counts. This reagent is intended to be used in a "no wash" protocol for flow cytometric analysis of erythrocytelysed human whole blood.

Technological Characteristics

The Dry Tri T-STAT (CD3/CD4/CD8) reagent, like the predicate devices, contains fluorescently labeled antibodies and fluorescent counting beads that are used to stain specific T-cell populations. These stained cells can be analyzed on any flow cytometer equipped with a 488nm laser, scattering detection, and capable of fluorescence detection in the ranges 515-545nm, 562-607nm, and >650nm.

Fluorescence from the CD4-A488, CD8-PE, and CD3-PE-D649 antibody conjugates can be detected in each of the three wavelength ranges when specifically bound to the cells. The counting beads can be used to determine the volume of sample analyzed on the flow cytometer when a precise volume of blood is dispensed into the tube containing the conjugates and a known number of beads. This allows the single platform determination of the absolute CD4+ and CD8+ T-cell counts.

Performance Characteristics

1. Precision/Reproducibility
  Within run reproducibility was determined by performing 10 replicates of a high, medium, and low count samples. The results were found to be acceptable with average %CV better than 10%.
1. Linearity
  The linearity was determined over the reportable ranges for CD4+ (65-1500 cells/ul) and CD8+ (50-1500 cells/ul) T-cells. The linearity was found to be acceptable with correlation coefficients greater than 0.99.
1. Sample stability
  Sample stability was assessed at 24 hour intervals from the time of phlebotomy. Sample stability with respect to absolute CD4+ and CD8+ T-cell concentrations were acceptable when analyzed 24 hours post draw. If samples were processed at the time of phlebotomy then the counts was found to be stable for 7 days.

4. Cross reactivity

The monoclonal antibodies used in the Dry Tri T-STAT (CD3/CD4/CD8) reagent were assigned these specificities at the International Workshops on Human Leukocyte Differentiation Antigens. Conjugation has not changed their specificities.

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1. Correlation to predicate devices
  The Dry Tri T-STAT (CD3/CD4/CD8) reagent was compared to the predicate devices at four different sites (291 samples). The correlation of absolute CD4+ & CD8+ T-cell counts were R2=0.99, 0.93, 0.91, & 0.99 and R2=0.96, 0.91, & 0.96, respectively.

Conclusion

The information presented in this pre-market notification for the Dry Tri T-STAT (CD3/CD4/CD8) reagent demonstrates substantial equivalence to the predicate devices.

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Food and Drug Administration 2098 Gaither Road Rockville MD 20850

RealMetrix, Inc. c/o Mr. Steve Kunitake Director 1585 Industrial Road San Carlos, CA 94070

Re: K082091

Trade/Device Name: Dry Tri T- STAT (CD3/CD4/CD8) reagent Regulation Number: 21 CFR 864.5220 Regulation Name: Automated Differential Cell Counter Regulatory Class: II Product Code: GKZ Dated: April 1, 2009 Received: April 6, 2009

APR 1 5 2009

Dear Mr. Kunitake:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate 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) that do not require approval of a premarket approval application (PMA). 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 (PMA). it may be subject to such additional controls. Existing major regulations affecting your device can be found in Title 21, Code of Federal Regulations (CFR), Parts 800 to 895. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Parts 801 and 809); and good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820). This letter will allow you to begin marketing your device as described in your Section 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.

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Page 2 - Mr. Steve Kunitake

your Section 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 vou desire specific advice for your device on the labeling regulation, please contact the Office of In Vitro Diagnostic Device Evaluation and Safety at 240- 276-0450. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For question regarding postmarket surveillance, please contact CDRH's Office of Surveillance and Biometric's (OSB's) Division of Postmarket Surveillance at 240-276-3474. For questions regarding the reporting of device adverse events (Medical Device Reporting (MDR), please contact the Division of Surveillance Systems at 240-276-3464. You many obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (240) 276-3150 or at its Internet address http://www.fda.gov/cdrh/industry/support/index.html.

Sincerely yours,

in chan

Maria M. Chan, Ph.D. Director

Division of Immunology and Hematology Devices Office of In Vitro Diagnostic Device Evaluation and Safety

Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known): K082091

Device Name: Dry Tri T-STAT (CD3/CD4/CD8) reagent

Indications For Use:

Prescription Use X (Part 21 CFR 801 Subpart D) AND/OR

Over-The-Counter Use (21 CFR 807 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of in Vitro Diagnostic Devices (OIVD)

Division Sign-Off
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Office of In Vitro Diagnostic Device Evaluation and Safety

510(k)	K082091
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Regulation Number and Section

§ 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.”