Histofluor Rodent LKS Fluorescent Antibody Test System, Image Navigator by Immuno Concepts
Device Facts
| Record ID | K180202 |
|---|---|
| Device Name | Histofluor Rodent LKS Fluorescent Antibody Test System, Image Navigator by Immuno Concepts |
| Applicant | Immuno Concepts, N.A. , Ltd. |
| Product Code | DBL · Immunology |
| Decision Date | Oct 19, 2018 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 866.5660 |
| Device Class | Class 2 |
| Attributes | Software as a Medical Device |
Indications for Use
This is an indirect fluorescent antibody test for the qualitative or semi-quantitative detection of IgG autoantibodies in human serum by manual fluorescent microscopy or with the Image Navigator Fluorescence Semi-Automated Microscope. This test system is to be used as an aid in the detection of anti-mitochondrial (AMA), anti-parietal cell (APCA), and anti-smooth muscle (ASMA) antibodies associated with Type 1 Autoimmune Hepatitis, Primary Biliary Cholangitis, and Pernicious Anemia/Autoimmune Gastritis in conjunction with other laboratory and clinical findings. A trained operator must confirm results generated with the Image Navigator semi-automated device and software.
Device Story
System comprises Histofluor Rodent LKS reagents and Image Navigator fluorescence semi-automated microscope. Input: human serum samples processed via indirect fluorescent antibody test on rodent tissue substrates. Image Navigator captures fluorescent images of slides; software processes images to assist in detection of autoantibodies. Operator reviews and confirms automated results. Used in clinical laboratory settings. Output: qualitative/semi-quantitative IgG autoantibody detection. Assists clinicians in diagnosing autoimmune conditions; improves workflow efficiency compared to manual microscopy.
Clinical Evidence
No clinical data provided. Substantial equivalence established via bench testing and performance evaluation of the assay system on the Image Navigator platform.
Technological Characteristics
System includes fluorescent antibody reagents and semi-automated fluorescence microscope. Connectivity: Image Navigator platform. Software: Image processing and analysis for fluorescence detection. Sterilization: Not applicable (reagents).
Indications for Use
Indicated for qualitative or semi-quantitative detection of IgG autoantibodies (AMA, APCA, ASMA) in human serum as an aid in diagnosing Type 1 Autoimmune Hepatitis, Primary Biliary Cholangitis, and Pernicious Anemia/Autoimmune Gastritis. For prescription use only by trained operators in clinical laboratories.
Regulatory Classification
Identification
A multiple autoantibodies immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoantibodies (antibodies produced against the body's own tissues) in serum and other body fluids. Measurement of multiple autoantibodies aids in the diagnosis of autoimmune disorders (disease produced when the body's own tissues are injured by autoantibodies).
Predicate Devices
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Submission Summary (Full Text)
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION MEMORANDUM
A. 510(k) Number:
K180202
B. Purpose for Submission:
New Assay
C. Measurand:
Human serum IgG autoantibodies to anti-mitochondrial (AMA), anti-parietal cell (APCA), and anti-smooth muscle (ASMA)
D. Type of Test:
Qualitative and/or Semi-quantitative indirect immunofluorescence; manual or semi-automated
E. Applicant:
Immuno Concepts, N.A., Ltd.
F. Proprietary and Established Names:
Histofluor Rodent LKS Fluorescent Antibody Test System
Image Navigator by Immuno Concepts
G. Regulatory Information:
1. Regulation section:
21 CFR §866.5660 – Multiple autoantibodies immunological test system (assay)
21 CFR §866.4750 – Automated indirect immunofluorescence microscope and software-assisted system (instrument)
2. Classification:
Class II (assay and instrument)
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3. Product code:
DBL, Multiple autoantibodies immunological test system
PIV, Automated indirect immunofluorescent microscope and software-assisted system for clinical use
4. Panel:
Immunology (82)
H. Intended Use:
1. Intended use(s):
This is an indirect fluorescent antibody test for the qualitative or semi-quantitative detection of IgG autoantibodies in human serum by manual fluorescent microscopy or with the Image Navigator Fluorescence Semi-Automated Microscope. This test system is to be used as an aid in the detection of anti-mitochondrial (AMA), anti-parietal cell (APCA), and anti-smooth muscle (ASMA) antibodies associated with Type 1 Autoimmune Hepatitis, Primary Biliary Cholangitis, and Pernicious Anemia/Autoimmune Gastritis in conjunction with other laboratory and clinical findings. A trained operator must confirm results generated with the Image Navigator semi-automated device and software.
2. Indication(s) for use:
Same as Intended Use
3. Special conditions for use statement:
1. For Prescription Use Only
2. This device is only for use with reagents that are indicated for use with the device
3. The device is for use by a trained operator in a clinical laboratory setting
4. All software-aided results must be confirmed by the trained operator
4. Special instrument requirements:
Optional use on either the semi-automated Image Navigator fluorescence microscopy system, or manual fluorescence microscopy. Immuno Concepts Image Navigator is a semi-automated system consisting of a fluorescent microscope and the software does not make result recommendations for the LKS assay. A trained operator must interpret the results.
I. Device Description:
The indirect fluorescent antibody kit to be used for detection of multiple autoantibodies is a
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device for use either in a conventional immunofluorescent assay or by analysis with the Image Navigator. The same kit, with no modifications, is used for both conventional and Image Navigator analysis.
| Histofluor Rodent LKS Fluorescent Antibody Test System Device Description | | |
| --- | --- | --- |
| Kit Component | Part Number | Description |
| Substrate Slides | 12004-02: 4-well mouse tissues | Multi-well 4-5 μm fixed sections of composite rodent liver, kidney, and stomach tissues on glass slides |
| | 12008-02: 8-well mouse tissues | |
| | 12004-03: 4-well rat tissues | |
| | 12008-03: 8-well rat tissues | |
| AMA positive control | 12021-02 | 1.0 mL positive control human serum with IgG antibodies specific to mitochondrial antigens |
| Negative control | 12031 | 1.0 mL human control serum |
| Fluorescent antibody reagent (conjugate) | 9.0 mL: 12009-0223 mL: 12075-02 | goat-anti-human IgG conjugated to FITC |
| Optional control reagents | | |
| APCA positive control | 12022-02 | 0.5 mL positive control human serum with IgG antibodies specific to gastric parietal cell antigens |
| ASMA positive control | 12023-02 | 0.5 mL positive control human serum with IgG antibodies specific to smooth muscle antigens |
| Optional titratable control reagents | | |
| AMA titratable control | 12261-02 | 0.25 mL undiluted positive control human serum with IgG antibodies specific to mitochondrial antigens |
| APCA titratable control | 12262-02 | 0.25 mL undiluted positive control human serum with IgG antibodies specific to gastric parietal cell antigens |
| ASMA titratable control | 12263-02 | 0.25 mL undiluted positive control human serum with IgG antibodies specific to smooth muscle antigens |
| Non-reactive components | | |
| PBS buffer powder | 1011 | phosphate-buffered saline powder (0.01M, pH 7.4±0.2), for 1L reconstituted buffer |
| Mounting medium | 1111 | 5.0 mL semi-permanent glycerol-based mounting medium |
| Coverslips | 1042 | 10 24×64 mm No. 1 glass coverslips |
Image Navigator is an automated scanning microscope and image presentation system. The
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system is comprised of a computer, monitor, keyboard, mouse, barcode readers, installed software, microscope, and digital camera. The automated microscope includes a motorized stage, autofocus drive, brightfield lamp, LED fluorescence lamp, eyepieces, condenser, and camera adapter. Images captured by the digital camera are transferred to the computer for entry into a file appropriate to the patient identification, and subsequent processing by the software. For this assay, Immuno Concepts Image Navigator does not make result recommendations. A trained operator must interpret the results.
# J. Substantial Equivalence Information:
1. Predicate device names:
MeDiCa IIF Multiple Antibody Test Kit (assay)
Image Navigator by Immuno Concepts (instrument)
2. Predicate 510(k) numbers:
K831100 (assay)
K160265 (instrument)
3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device (K180202) | Assay Predicate (K831100) |
| Methodology | Indirect immunofluorescence (IFA) | Same |
| Substrate | Rodent (rat, mouse) liver + kidney + stomach | Same |
| Starting Dilution | 1:20 | Same |
| Assay Cutoff | 1:20 | Same |
| Sample Matrix | Serum | Same |
| Conjugate | Goat anti-human IgG FITC | Same |
| Results | qualitative, pattern, semi-quantitative, titer | Same |
| Item | Device (K180202) | Instrument Predicate (K160265) |
| Software | Automated image acquisition and digital display for semi-automated image interpretation | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device (K180202) | Assay Predicate (K831100) |
| Intended Use | This is an indirect fluorescent antibody test for the semi-quantitative detection of IgG antibodies in human serum by manual fluorescent microscopy or with the Image Navigator | MeDiCa Indirect Immunofluorescence (IIF) Antibody Test Kits are used for the qualitative and semi-quantitative detection of specific Ig classes of autoantibodies in |
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| Differences | | |
| --- | --- | --- |
| Item | Device (K180202) | Assay Predicate (K831100) |
| | Fluorescence Semi-Automated Microscope. This test system is to be used as an aid in the detection of antibodies associated with autoimmune diseases in conjunction with other laboratory and clinical findings. A trained operator must confirm results generated with the Image Navigator semi-automated device and software. | human serum as an aid in the diagnosis of certain pathologies. |
| Measurands | Human serum IgG autoantibodies: anti-mitochondrial (AMA) anti-parietal cell (APCA) anti-smooth muscle (ASMA) | AMA, APCA, ASMA, and anti-nuclear antibodies (ANA) |
| Instrument | The Image Navigator is an optional automated microscope designed to acquire and display images for the user | Conventional fluorescent microscopy |
| Item | Device (K180202) | Instrument Predicate (K160265) |
| Software | Image Navigator does not provide recommended qualitative outcome (i.e. positive or negative) to the user following image acquisition | Image Navigator makes recommendations to the user for qualitative outcomes (i.e. positive or negative) following image acquisition |
| Image Acquisition & Processing | Capture of 16 images of 100× total magnification, stitched into single image | Capture of 4 images at 200× total magnification, stitched into single image |
| Image Evaluation | Operator-dependent | Software recommendation of (+) or (-) value to operator |
K. Standard/Guidance Document Referenced:
| Org | Standard ID | Version | Date | Title |
| --- | --- | --- | --- | --- |
| CLSI | EP07 | A2 | Dec 2002 | Interference Testing in Clinical Chemistry |
# L. Test Principle:
The Immuno Concepts Histofluor Rodent LKS Test System uses the indirect fluorescent antibody technique. Patient samples are incubated on substrate slides with composite liver/kidney/stomach (LKS) tissue sections from mouse or rat to allow specific binding of autoantibodies to cell components. If autoantibodies are present, a stable antigen-antibody complex is formed. After washing to remove non-specific and unbound antibodies, the
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sample is incubated with an anti-human antibody conjugated to fluorescein. If autoantibodies are present, autoantibodies bound to the substrate can be visualized with the aid of a fluorescent microscope, with a staining pattern characteristic of the antigen distribution within cells or tissues. If the sample is negative for autoantibodies, the substrate will not show a clearly discernible pattern of fluorescence.
## M. Performance Characteristics:
### 1. Analytical performance:
#### a. Precision/Reproducibility:
Multi-site reproducibility studies were performed on 13 patient serum samples representing four each of the three patterns (AMA, APCA, ASMA) and one negative sample. For each pattern, the samples were low titer, medium titer, and high titer. For both manual and semi-automated Image Navigator reading modes, for both substrate species, two users/site at three sites read each sample in triplicate over 10 runs for a total of 312 datapoints.
Based on these outcomes, agreement measures for endpoint titer and pattern were within pre-specified acceptance criteria; the lower confidence interval bounds for all pairwise comparisons on each substrate, in either reading mode were all $\geq 88.6\%$. Agreement measures for endpoint titer and pattern identification between users and between sites are presented in the tables below:
Endpoint Titer Agreement between Readers:
| Reproducibility: Mouse, Manual Mode – % Titer Agreement (±1 titer), with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 97.8% (95.6–99.0%) | 97.2% (94.9–98.6%) | 90.3% (86.8–93.0%) | 96.7% (94.2–98.1%) | 98.3% (96.3–99.3%) |
| | User 2 | | | 99.4% (97.9–100%) | 95.6% (92.9–97.3%) | 98.1% (96.0–99.1%) | 98.9% (97.1–99.7%) |
| Site 2 | User 1 | | | | 94.2% (91.2–96.2%) | 97.8% (95.6–99.0%) | 98.6% (96.7–99.5%) |
| | User 2 | | | | | 92.2% (89.0–94.6%) | 91.9% (88.6–94.4%) |
| Site 3 | User 1 | | | | | | 98.1% (96.0–99.1%) |
| | User 2 | | | | | | |
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| Reproducibility: Mouse, Semi-Automated – % Titer Agreement (±1 titer), with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 98.6% (96.7–99.5%) | 98.9% (97.1–99.7%) | 95.6% (92.9–97.3%) | 98.6% (96.7–99.5%) | 99.4% (97.9–100%) |
| | User 2 | | | 98.6% (96.7–99.5%) | 95.0% (92.2–96.9%) | 98.6% (96.7–99.5%) | 98.6% (96.7–99.5%) |
| Site 2 | User 1 | | | | 96.7% (94.2–98.1%) | 98.6% (96.7–99.5%) | 99.4% (97.9–100%) |
| | User 2 | | | | | 93.6% (90.6–95.8%) | 95.6% (92.9–97.3%) |
| Site 3 | User 1 | | | | | | 99.4% (97.9–100%) |
| | User 2 | | | | | | |
| Reproducibility: Rat, Manual Mode – % Titer Agreement (±1 titer), with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 96.1% (93.5–97.7%) | 97.2% (94.9–98.6%) | 96.1% (93.5–97.7%) | 96.7% (94.2–98.1%) | 95.8% (93.2–97.5%) |
| | User 2 | | | 97.2% (94.9–98.6%) | 95.6% (92.9–97.3%) | 96.7% (94.2–98.1%) | 95.0% (92.2–96.9%) |
| Site 2 | User 1 | | | | 97.2% (94.9–98.6%) | 98.3% (96.3–99.3%) | 98.3% (96.3–99.3%) |
| | User 2 | | | | | 97.8% (95.6–99.0%) | 94.7% (91.9–96.6%) |
| Site 3 | User 1 | | | | | | 95.8% (93.2–97.5%) |
| | User 2 | | | | | | |
| Reproducibility: Rat, Semi-Automated – % Titer Agreement (±1 titer), with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 95.8% (93.2–97.5%) | 95.8% (93.2–97.5%) | 95.6% (92.9–97.3%) | 98.1% (96.0–99.1%) | 95.0% (92.2–96.9%) |
| | User 2 | | | 96.4% (93.9–97.9%) | 94.7% (91.9–96.6%) | 96.7% (94.2–98.1%) | 95.6% (92.9–97.3%) |
| Site 2 | User 1 | | | | 96.4% (93.9–97.9%) | 98.3% (96.3–99.3%) | 98.1% (96.0–99.1%) |
| | User 2 | | | | | 96.9% (94.6–98.4%) | 95.3% (92.5–97.1%) |
| Site 3 | User 1 | | | | | | 97.2% (94.9–98.6%) |
| | User 2 | | | | | | |
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Pattern Agreement between Readers:
| Reproducibility: Mouse, Manual Mode – % Pattern Agreement, with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 100% (98.7–100%) | 100% (98.7–100%) | 99.7% (98.3–99.9%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | 100% (98.7–100%) | 99.7% (98.3–99.9%) | 100% (98.7–100%) | 100% (98.7–100%) |
| Site 2 | User 1 | | | | 99.7% (98.3–99.9%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | | | 99.7% (98.3–99.9%) | 99.7% (98.3–99.9%) |
| Site 3 | User 1 | | | | | | 100% (98.7–100%) |
| | User 2 | | | | | | |
| Reproducibility: Mouse, Semi-Automated – % Pattern Agreement, with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 100% (98.7–100%) | 100% (98.7–100%) | 99.7% (98.3–99.9%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | 100% (98.7–100%) | 99.7% (98.3–99.9%) | 100% (98.7–100%) | 100% (98.7–100%) |
| Site 2 | User 1 | | | | 99.7% (98.3–99.9%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | | | 99.7% (98.3–99.9%) | 99.7% (98.3–99.9%) |
| Site 3 | User 1 | | | | | | 100% (98.7–100%) |
| | User 2 | | | | | | |
| Reproducibility: Rat, Manual Mode – % Pattern Agreement, with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) |
| Site 2 | User 1 | | | | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | | | 100% (98.7–100%) | 100% (98.7–100%) |
| Site 3 | User 1 | | | | | | 100% (98.7–100%) |
| | User 2 | | | | | | |
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| Reproducibility: Rat, Semi-Automated – % Pattern Agreement, with 95% CI | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | Site 1 | | Site 2 | | Site 3 | | |
| | | User 1 | User 2 | User 1 | User 2 | User 1 | User 2 |
| Site 1 | User 1 | | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) |
| Site 2 | User 1 | | | | 100% (98.7–100%) | 100% (98.7–100%) | 100% (98.7–100%) |
| | User 2 | | | | | 100% (98.7–100%) | 100% (98.7–100%) |
| Site 3 | User 1 | | | | | | 100% (98.7–100%) |
| | User 2 | | | | | | |
Lot-to-lot precision was evaluated using both manual and semi-automated reading modes using three lots of each substrate (mouse or rat) $\times 32$ samples $\times$ three readers. Samples were selected to represent all three patterns (i.e. AMA, APCA, ASMA), across the range of titers.
| Lot-to-lot precision (% with 95% CI) | | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Substrate | Measure | n | Manual | | | Semi-automated | | |
| | | | Lot 1 v 2 | Lot 1 v 3 | Lot 2 v 3 | Lot 1 v 2 | Lot 1 v 3 | Lot 2 v 3 |
| Mouse | PPA | 30 | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) |
| | NPA | 2 | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) |
| | Pattern | 30 | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) | 100% (86.5–100%) |
| | ±1 Titer | 30 | 96.7% (81.9–100%) | 96.7% (81.9–100%) | 96.7% (81.9–100%) | 90.0% (73.6–97.3%) | 96.7% (81.9–100%) | 100% (86.5–100%) |
| Rat | PPA | 30 | 100% (86.5–100%) | 96.7% (81.9–100%) | 96.7% (81.9–100%) | 100% (86.5–100%) | 96.7% (81.9–100%) | 96.7% (81.9–100%) |
| | NPA | 2 | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) | 100% (29.0–100%) |
| | Pattern | 30 | 100% (86.5–100%) | 96.7% (81.9–100%) | 96.7% (81.9–100%) | 100% (86.5–100%) | 96.7% (81.9–100%) | 96.7% (81.9–100%) |
| | ±1 Titer | 30 | 93.3% (77.6–99.2%) | 96.7% (81.9–100%) | 93.3% (77.6–99.2%) | 100% (86.5–100%) | 93.3% (77.6–99.2%) | 90.0% (73.6–97.3%) |
b. Linearity/assay reportable range:
To assess endpoint titration, one sample from each of the target patterns (AMA, APCA, and ASMA) was evaluated on Histofluor Mouse and Rat Tissue slides. The sample was assayed in duplicate and analyzed by two readers using both conventional and semi-automated reading methods. A consistent pattern was found throughout the
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titer to the endpoint and a consistent titer endpoint was found between readers and methods (within ±1 titer).
Mouse Substrate:
| Expected Pattern | Replicate | Manual | | | | Semi-Automated | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Reader 1 | | Reader 2 | | Reader 1 | | Reader 2 | |
| | | Pattern | Titer | Pattern | Titer | Pattern | Titer | Pattern | Titer |
| ASMA | 1 | ASMA | 1:640 | ASMA | 1:320 | ASMA | 1:320 | ASMA | 1:320 |
| AMA | 1 | AMA | 1:80 | AMA | 1:80 | AMA | 1:80 | AMA | 1:80 |
| APCA | 1 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 |
| ASMA | 2 | ASMA | 1:640 | ASMA | 1:320 | ASMA | 1:320 | ASMA | 1:320 |
| AMA | 2 | AMA | 1:160 | AMA | 1:80 | AMA | 1:80 | AMA | 1:80 |
| APCA | 2 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 |
Rat Substrate:
| Expected Pattern | Replicate | Manual | | | | Semi-Automated | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Reader 1 | | Reader 2 | | Reader 1 | | Reader 2 | |
| | | Pattern | Titer | Pattern | Titer | Pattern | Titer | Pattern | Titer |
| ASMA | 1 | ASMA | 1:640 | ASMA | 1:640 | ASMA | 1:320 | ASMA | 1:320 |
| AMA | 1 | AMA | 1:160 | AMA | 1:80 | AMA | 1:80 | AMA | 1:80 |
| APCA | 1 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 |
| ASMA | 2 | ASMA | 1:640 | ASMA | 1:320 | ASMA | 1:320 | ASMA | 1:320 |
| AMA | 2 | AMA | 1:160 | AMA | 1:80 | AMA | 1:160 | AMA | 1:80 |
| APCA | 2 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 | APCA | 1:80 |
c. Traceability, Stability, Expected values (controls, calibrators, or methods):
Recognized consensus, traceable reference standards are not available for AMA, APCA, or ASMA autoantibodies.
Real-time stability studies demonstrated shelf-life of the Histofluor rodent LKS assays to a minimum 12 months at $2 - 10^{\circ}\mathrm{C}$ . Open-kit stability studies supported in-use stability to a minimum of 8 weeks at at $2 - 10^{\circ}\mathrm{C}$ . Stability studies evaluated comparable qualitative (positive/negative), pattern identification, and endpoint titer $(\pm 1$ dilution) outcomes.
d. Detection limit:
For semi-quantitative IFA, detection limits are not applicable.
e. Analytical specificity:
Cross-Reactivity
Potentially cross-reactive disease sera were tested for LKS autoantibodies using the
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Histofluor LKS IFA including 121 samples from other autoimmune diseases (autoimmune thyroiditis, celiac disease, Crohn's and IBS, type 1 diabetes, systemic sclerosis, Sjögren's syndrome, systemic lupus erythematosus, rheumatoid arthritis, and autoimmune vasculitis); lymphoma; cirrhosis from causes other than AIH or PBC; Helicobacter pylori infection; HBV and HCV. Positive prevalence in these cohorts was as expected in literature and comparable to the predicate device. See Section M.3, below for the results of these studies.
## Interference
The sponsor claimed conformance to CLSI EP07-A2. Three specimens were tested, one negative, one medium-titer positive (1:320), and one high-titer positive (1:1280) in triplicate for three concentrations of each of five interferents. Interferents were spiked by predilution and addition of 10% (v/v) of final total sample volume. Controls were diluted with unspiked 10% (v/v) diluent.
All samples were tested on mouse LKS slides and evaluated by both manual and semi-automated reading modes by three operators. Fluorescence of samples containing the interfering substances were within ± one intensity grade of the control samples with both reading modes. No interference was detected with bilirubin up to 10 mg/dL, hemoglobin up to 200 mg/dL, triglycerides up to 1000 mg/dL, cholesterol up to 230 mg/dL, ampicillin (as a representative cholestatic) up to 152 μM, omeprazole (as a representative proton pump inhibitor) up to 17.4 μM, and rheumatoid factor IgM up to 60 units.
f. Assay cut-off:
Clinical performance studies evaluated a 1:20 cutoff.
2. Comparison studies:
a. Method comparison:
One-hundred seventy clinical patient samples (see Section M.3 below) were tested in parallel on the Histofluor LKS substrates and the predicate assay at three sites for consensus adjudication. Positive percent agreement (PPA) and negative percent agreement (NPA) values were calculated, with 95% confidence intervals. Agreement of pattern identity calls was also evaluated for positive samples, as was agreement of endpoint titer, within agreement defined as within ±1 dilution.
Comparison results are presented in the following table, comparing the Histofluor LKS to the predicate using manual, conventional fluoromicroscopy methods; and the manual, conventional fluoromicroscopy to the software-assisted semi-automated reading mode for the Histofluor LKS substrates:
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| | Method Comparisons | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | | n | Histofluor LKS v Predicate | | Histofluor LKS | |
| | | | Manual | | Manual v Semi-Automated | |
| | | | % Agreement | (95% CI) | % Agreement | (95% CI) |
| Mouse | PPA | 36 | 94.4% | (80.9–99.4%) | 100% | (88.5–100%) |
| | NPA | 137 | 98.5% | (94.5–99.9%) | 100% | (96.7–100%) |
| | Pattern1 | 36 | 94.4% | (80.9–99.4%) | 100% | (88.5–100%) |
| | ±1 Titer | 36 | 80.6% | (64.7–90.6%) | 100% | (88.5–100%) |
| Rat | PPA | 39 | 92.3% | (79.0–98.1%) | 100% | (88.5–100%) |
| | NPA | 134 | 97.8% | (93.4–99.5%) | 100% | (96.6–100%) |
| | Pattern1 | 39 | 92.3% | (79.0–98.1%) | 100% | (87.9–100%) |
| | ±1 Titer | 39 | 76.9% | (61.5–87.6%) | 100% | (87.9–100%) |
1 Pattern identity calls represent agreement of qualitatively positive (+) samples
# b. Matrix comparison:
Serum is the only claimed, validated sample matrix.
# 3. Clinical studies:
Forty-nine samples from Intended Use indications (i.e. type 1 autoimmune hepatitis [AIH-1], pernicious anemia/autoimmune gastritis [PA/AG], and primary biliary cholangitis [PBC]) and 121 differential diagnosis samples described in Section M.1.e were tested on the Histofluor Rodent LKS IFA. Sensitivity and specificity were calculated from these 170 total samples and summarized just below, with a more detailed analysis in Section M.3.a and b. below.
| Disease and control samples tested by the Histofluor Mouse LKS in manual reading mode | | | | |
| --- | --- | --- | --- | --- |
| | AIH, PA/AG, PBC | | | |
| | | (+) | | (-) |
| Histofluor Mouse LKS | LKS(+) | 29 | 7 | 36 |
| | LKS(-) | 20 | 114 | 134 |
| | | 49 | 121 | 170 |
Sensitivity (95% CI): 59.2% (45.2 - 71.8%)
Specificity (95% CI): 94.2% (88.3 - 97.4%)
| Disease and control samples tested by the Histofluor Rat LKS in manual mode | | | | |
| --- | --- | --- | --- | --- |
| | AIH, PA/AG, PBC | | | |
| | | (+) | | (-) |
| Histofluor Rat LKS | LKS(+) | 30 | 7 | 37 |
| | LKS(-) | 19 | 114 | 133 |
| | | 49 | 121 | 170 |
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Sensitivity (95% CI): 61.2% (47.2 - 73.6%)
Specificity (95% CI): 94.2% (88.5 - 97.2%)
Values were comparable to results obtained using the predicate device.
# a. Clinical Sensitivity:
A total of 49 samples from the intended use indications were tested at three sites and read by three operators at each site.
| Clinical Sensitivity (% Se) | | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| Disease | n | Manual | | Semi-automated | | |
| | | % Se | (95% CI) | % Se | (95% CI) | |
| Mouse | All | 49 | 59.2% | (45.3–71.8%) | 59.2% | (45.2–71.8%) |
| | Autoimmune Hepatitis1 | 19 | 47.4% | (27.3–68.3%) | 47.4% | (27.3–68.3%) |
| | Pernicious Anemia/Autoimmune Gastritis2 | 12 | 41.7% | (19.3–68.1%) | 41.7% | (19.3–68.1%) |
| | Primary Biliary Cholangitis | 18 | 83.3% | (60.0–95.0%) | 83.3% | (60.0–95.0%) |
| Rat | All | 49 | 61.2% | (47.2–73.6%) | 61.2% | (47.2–73.6%) |
| | Autoimmune Hepatitis1 | 19 | 47.4% | (27.3–68.3%) | 47.4% | (27.3–68.3%) |
| | Pernicious Anemia/Autoimmune Gastritis2 | 12 | 50.0% | (25.4–74.6%) | 50.0% | (25.4–74.6%) |
| | Primary Biliary Cholangitis | 18 | 83.3% | (60.0–95.0%) | 83.3% | (60.0–95.0%) |
| 1AIH positives represent both ASMA and AMA patterns 2cohort combines patients with either pernicious anemia or autoimmune gastritis diagnoses; represent both APCA and ASMA patterns | | | | | | |
# b. Clinical specificity:
One-hundred twenty one clinically characterized samples were tested at three sites and read by three operators at each. Values represent consensus adjudication $(>2 / 3)$ reads.
| Clinical Specificity (% Sp) | | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| Disease | n | Manual | | Semi-automated | | |
| | | % Sp | (95% CI) | % Sp | (95% CI) | |
| Mouse | Autoimmune thyroid disease3 | 10 | 94.2% | (88.3–97.4%) | 94.2% | (88.3–97.4%) |
| | Lymphoma | 9 | | | | |
| | Celiac disease | 10 | | | | |
| | Cirrhosis4 | 2 | | | | |
| | Helicobacter pylori | 10 | | | | |
| | IBS, Crohn's disease | 10 | | | | |
| | Type 1 diabetes | 10 | | | | |
| | HBV, HCV | 10 | | | | |
| | Systemic sclerosis | 10 | | | | |
| | Sjögren's syndrome | 10 | | | | |
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| Clinical Specificity (% Sp) | | | | | |
| --- | --- | --- | --- | --- | --- |
| Disease | n | Manual | | Semi-automated | |
| | | % Sp | (95% CI) | % Sp | (95% CI) |
| Systemic lupus erythematosus | 10 | | | | |
| Rheumatoid arthritis | 10 | | | | |
| Autoimmune vasculitis^{5} | 10 | | | | |
| Rat | Autoimmune thyroid disease^{3} | 10 | 93.4% | (87.3–96.8%) | 93.4% |
| | Lymphoma | 9 | | | |
| | Celiac disease | 10 | | | |
| | Cirrhosis^{4} | 2 | | | |
| | Helicobacter pylori | 10 | | | |
| | IBS, Crohn’s disease | 10 | | | |
| | Type 1 diabetes | 10 | | | |
| | HBV, HCV | 10 | | | |
| | Systemic sclerosis | 10 | | | |
| | Sjögren’s syndrome | 10 | | | |
| | Systemic lupus erythematosus | 10 | | | |
| | Rheumatoid arthritis | 10 | | | |
| | Autoimmune vasculitis^{5} | 10 | | | |
| 3 diagnostic category includes Hashimoto’s/lymphocytic and Graves’ thyroiditis
4 cohort excludes AIH, PBC patients
5 diagnostic category includes biopsy-verified samples | | | | | |
c. Other clinical supportive data (when a. and b. are not applicable):
Not applicable
4. Clinical cut-off:
Same as assay cutoff (M.1.f)
5. Expected values/Reference range:
Samples from a cohort of 120 apparently healthy subjects (84 females and 36 males) were tested at 3 sites by two readers:
| Reference Range | | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| Dx | n | Manual | | Semi-automated | | |
| | | % (+) | (95% CI) | % (+) | (95% CI) | |
| Mouse | “apparently healthy subjects” | 120 | 1.7% | (0.1–6.2%) | 1.7% | (0.1–6.2%) |
| Rat | | | 1.7% | (0.1–6.2%) | 1.7% | (0.1–6.2%) |
The 2/120 positive samples in this study produced an APCA pattern at > 1:160 titer.
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N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Parts 801 and 809, as applicable, and the special controls for this device type under 21 CFR 866.5180.
O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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