(101 days)
ImmuKnow®-the Cylex®™Immune Cell Function Assay measures the concentration of ATP from circulating CD4 cells following in vitro stimulation with phytohemagglutinin (PHA) as an indicator of immune cell function. This measurement is made on heparin anti-coagulated whole blood using a luminometer and luciferin/luciferase. The assay is used for the detection of cell mediated immune response in populations undergoing immunosuppressive therapy for organ transplant.
The Cylex Immune Cell Function Assay measures the concentration of ATP from circulating CD4 cells following in vitro stimulation with phytohemagglutinin (PHA) as an indicator of immune cell function. This measurement is made on heparin anti-coagulated whole blood using a luminometer and luciferin/luciferase. The assay is used for the detection of cell mediated immune response in populations undergoing immunosuppressive therapy for organ transplant.
Test Description The Cylex Immune Cell Function Assay detects cell-mediated immunity in whole blood after a 15-18 hour incubation with stimulant. During incubation, increased ATP synthesis occurs within the cells that respond to the stimulant phytohemagglutinin (PHA). Concurrently, whole blood is incubated in the absence of stimulant for the purpose of assessing basal ATP activity. Anti-CD4 monoclonal antibody coated magnetic particles are added to immunoselect CD4 cells from both the stimulated and non-stimulated wells. After washing the selected CD4 cells on a magnet tray, Lysis Reagent is added to release intracellular ATP. Addition of Luminescence Reagent (luciferin/luciferase) to the released ATP produces light according to the following equation:
Mg24 Luciferin +ATP +O2 Luciferase Oxyluciferin +AMP +Pyrophosphate +CO2 + Light
The amount of light measured by a luminometer (emission maximum 562 nm) is proportional to the concentration of ATP. The concentration of ATP (ng/mL) is calculated from a calibration curve and compared to ATP level ranges to characterize the cellular immune function of the sample.
{
"1. A table of acceptance criteria and the reported device performance": {
"Acceptance Criteria": "The study aims to demonstrate substantial equivalence to predicate devices (Becton Dickinson TriTest™ CD4 FITC/CD8 PE/CD3 PerCP Reagent and MultiTest™ CD3 FITC/CD8 PE/CD45 PerCP/CD4 ACP Reagent) by showing that the Cylex Immune Cell Function Assay differentiates CD4 cells and determines their responsiveness.",
"Reported Device Performance": {
"Comparison of Population Means (ATP Results)": {
"Apparently Healthy (n=44)": "Mean/SD: 449/152 ng/mL, Median: 430 ng/mL, Range: 205-967 ng/mL",
"Transplant (n=78)": "Mean/SD: 274/166 ng/mL, Median: 251 ng/mL, Range: 21-759 ng/mL"
},
"Cross-Tabulation of Cylex Immune Cell Function Assay Results (Threshold ≤ 260 ng/mL)": {
"Transplant Subjects": "41 cases ≤ 260, 37 cases > 260",
"Normal Subjects": "4 cases ≤ 260, 40 cases > 260",
"Total": "122 subjects"
},
"Cross-Tabulation of Becton Dickinson Total CD4 count by Flow Cytometry Results (Threshold ≤ 350)": {
"Transplant Subjects": "33 cases ≤ 350, 45 cases > 350",
"Normal Subjects": "5 cases ≤ 350, 39 cases > 350",
"Total": "122 subjects"
},
"Conclusion": "The means of the two populations (apparently healthy and transplant) were found to be statistically different by the Cylex assay, indicating its ability to detect differences in immune cell function. The tables show a differentiation between transplant and normal subjects based on ATP results, which supports the claim of detecting cell-mediated immune response."
}
},
"2. Sample sized used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)": {
"Sample Size for Test Set": "122 subjects (44 apparently healthy adults and 78 transplant recipients).",
"Data Provenance": "Multi-center study on freshly drawn blood. No specific country of origin is mentioned, but the context of an FDA submission implies it was likely conducted in the US. The description 'freshly drawn blood' indicates a prospective or near-prospective data collection method for the purpose of this study."
},
"3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)": "Not applicable. The ground truth in this study is based on physiological measurements (ATP concentration) and patient status (apparently healthy vs. transplant recipient), not on expert interpretation of imaging or other complex data requiring multiple experts.",
"4. Adjudication method (e.g. 2+1, 3+1, none) for the test set": "Not applicable. Ground truth is established by objective physiological measurements and known patient status, not by expert adjudication.",
"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": "Not applicable. This is a study evaluating the performance of a diagnostic assay (Cylex Immune Cell Function Assay), not an AI-assisted diagnostic tool for human readers.",
"6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done": "Yes, a standalone study was done. The Cylex Immune Cell Function Assay measures ATP concentration to indicate immune cell function independently.",
"7. The type of ground truth used (expert concensus, pathology, outcomes data, etc)": "The ground truth is based on two types of data: 1) the physiological measurement of ATP concentration from circulating CD4 cells after stimulation and 2) the known clinical status of the patients (apparently healthy vs. transplant recipient). The Becton Dickinson Total CD4 count by Flow Cytometry is also used as a comparative measure from a predicate device.",
"8. The sample size for the training set": "Not specified. The provided text describes a study for substantial equivalence, which primarily focuses on validation/test data. Information regarding a separate training set for algorithm development is not included.",
"9. How the ground truth for the training set was established": "Not specified, as information about a training set is not provided."
}
§ 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.”