DSDNA IMMUNOGLOBULIN EIA TEST SYSTEM
K960182 · Mardx Diagnostics, Inc. · LRM · Mar 20, 1996 · Immunology
Device Facts
| Record ID | K960182 |
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| Device Name | DSDNA IMMUNOGLOBULIN EIA TEST SYSTEM |
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| Applicant | Mardx Diagnostics, Inc. |
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| Product Code | LRM · Immunology |
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| Decision Date | Mar 20, 1996 |
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| Decision | SESE |
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| Submission Type | Traditional |
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| Regulation | 21 CFR 866.5100 |
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| Device Class | Class 2 |
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Intended Use
The assay is intended for use in detecting antibodies in a single serum specimen. The results of the assay are to be used as an aid in the diagnosis of Systemic Lupus Erythematosus (SLE).
Device Story
The dsDNA Immunoglobulin EIA test system is an enzyme-linked immunosorbent assay (EIA) used to detect and semi-quantitate antibodies to dsDNA in human serum. Purified dsDNA antigens are immobilized on microtiter wells; patient serum is added, allowing specific antibodies to bind. After washing, an enzyme-labeled anti-human Immunoglobulin conjugate is added, followed by a substrate solution. The resulting color change is measured photometrically, providing an indirect measurement of antibody concentration. The device is used in clinical laboratory settings by trained personnel. Results are interpreted by healthcare providers to aid in the diagnosis of Systemic Lupus Erythematosus (SLE).
Clinical Evidence
Clinical evaluation compared the MarDx dsDNA EIA to a commercially available dsDNA ELISA using 133 patient specimens (88 normal, 45 autoimmune). Results showed 95.0% relative sensitivity, 100% relative specificity, and 98.3% relative accuracy. Precision was evaluated across three days (n=30), with inter-assay CVs ranging from 4.67% to 17.78%. Linearity was confirmed via serial dilution (r=0.959-0.989). Cross-reactivity testing against Ro, La, SM, RNP, SCL-70, and Jo-1 showed minimal interference.
Technological Characteristics
Enzyme-linked immunosorbent assay (EIA) using purified dsDNA antigens immobilized on solid-phase microtiter wells. Detection utilizes enzyme-labeled anti-human Immunoglobulin conjugate and a substrate solution. Measurement is performed via photometric analysis of color intensity. The system is a manual or semi-automated laboratory assay.
Indications for Use
Indicated for the detection and semi-quantitation of Immunoglobulin to dsDNA in human serum specimens to aid in the diagnosis of Systemic Lupus Erythematosus (SLE).
Regulatory Classification
Identification
An antinuclear antibody immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoimmune antibodies in serum, other body fluids, and tissues that react with cellular nuclear constituents (molecules present in the nucleus of a cell, such as ribonucleic acid, deoxyribonucleic acid, or nuclear proteins). The measurements aid in the diagnosis of systemic lupus erythematosus (a multisystem autoimmune disease in which antibodies attack the victim's own tissues), hepatitis (a liver disease), rheumatoid arthritis, Sjögren's syndrome (arthritis with inflammation of the eye, eyelid, and salivary glands), and systemic sclerosis (chronic hardening and shrinking of many body tissues).
Predicate Devices
- Clark ELISA for dsDNA IgG, IgM antibodies
Related Devices
- K974694 — IS-DSDNA TEST SYSTEM · Diamedix Corp. · Mar 3, 1998
- K994424 — DIAMEDIX IS-ANTI-DSDNA TEST SYSTEM · Diamedix Corp. · Feb 18, 2000
- K980391 — SERAQUEST ANTI-DSDNA · Quest Intl., Inc. · Apr 24, 1998
- K101319 — IMMULISA DSDNA ANTIBODY ELISA · Immco Diagnostics, Inc. · Dec 9, 2010
- K081251 — MODIFICATION TO AESKULISA DS DNA G · Aesku Diagnostics · May 13, 2008
Submission Summary (Full Text)
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MARDX Diagnostics, Inc., 5919 Farnsworth Ct, Carlsbad, CA 92008 • 800-331-2291 • CA: 619-929-0500 • FAX: 619-929-0124
MAR 20 1996
# 510(k) Summary of Safety and Effectiveness Information
## dsDNA EIA Test System K960182
This summary of 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and proposed 21 CFR Part 807.92.
### Identification of predicate device:
The dsDNA Immunoglobulin EIA test system is substantially equivalent to the Clark ELISA for dsDNA IgG, IgM antibodies.
### Description of New Device
The dsDNA Immunoglobulin EIA test system is an enzyme-linked immunosorbent assay (EIA) for the detection and semi-quantitation of Immunoglobulin to dsDNA in human sera.
### Statement of the intended use:
The assay is intended for use in detecting antibodies in a single serum specimen. The results of the assay are to be used as an aid in the diagnosis of Systemic Lupus Erythematosus (SLE).
### Technological characteristics of the device:
The dsDNA Immunoglobulin EIA test system is an enzyme linked immunosorbent assay to detect Immunoglobulin, to dsDNA. Purified dsDNA antigens are attached to a solid phase microtiter well. Diluted test sera is added to each well. If the antibodies are present that recognize the antigen, they will bind to the antigen in the well. After incubation the wells are washed to remove unbound antibody. An enzyme labeled anti-human Immunoglobulin is added to each well. If antibody is present it will bind to the antibody attached to the antigen on well. After incubation, the wells are washed to remove unbound conjugate. A substrate solution is added to each well. If enzyme is present, the substrate will undergo a color change. After an incubation period, the reaction is stopped and the color intensity is measured photometrically, producing an indirect measurement of specific antibody in the patient specimen.
### Description and conclusions of the clinical studies:
The dsDNA Immunoglobulin EIA Test System is substantially equivalent to the Clark ELISA for dsDNA IgG, IgM antibodies. Equivalence is demonstrated by the following comparative results:
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total of 133 patient specimens were obtained. Eighty-eight of the specimens were from normal individuals. Forty-five specimens were thought to have autoimmune disease. The serum were evaluated relative to a commercially available dsDNA ELISA assay. The results were shown in Table 1.
Table 1 Sensitivity and Specificity of the MarDx dsDNA EIA relative to Clark dsDNA test
MarDx dsDNA EIA
| | | + | eq | - | Total |
| --- | --- | --- | --- | --- | --- |
| | + | 38 | 7 | 2* | 47 |
| Alternate EIA | eq | 0 | 0 | 2 | 2 |
| | - | 0 | 3 | 81 | 84 |
| | Total | 38 | 10 | 85 | 133 |
Sera falling in the equivocal range were not included in the following calculations. These 2 sera were tested by Crithidia IFA and found to be negative.
Relative Sensitivity $= 38 / 40$ $= 95.0\%$
Relative Specificity $= 81 / 81$ $= 100\%$
Relative Accuracy $= 119 / 121$ $= 98.3\%$
The MarDx EIA was evaluated for precision by testing seven sera ten times each on three different days. The results are summarized in Table 2.
Table 2 Precision of the MarDx EIA Test
| | Assay 1 (n=10) | | | Assay 2 (n=10) | | | Assay 3 (n=10) | | | Inter Assay (n=30) | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | X | SD | CV | X | SD | CV | X | SD | CV | X | SD | CV |
| 1 | 7.78 | 0.252 | 3.24% | 8.10 | 0.329 | 4.06% | 7.31 | 0.237 | 3.24% | 7.73 | 0.424 | 5.48% |
| 2 | 8.07 | 0.188 | 2.32% | 8.48 | 0.306 | 3.61% | 7.77 | 0.222 | 2.88% | 8.11 | 0.379 | 4.67% |
| 3 | 4.78 | 0.324 | 6.78% | 4.78 | 0.390 | 8.15% | 4.37 | 0.272 | 6.22% | 4.64 | 0.376 | 8.11% |
| 4 | 3.77 | 0.260 | 6.90% | 3.85 | 0.213 | 5.53% | 3.81 | 0.213 | 5.59% | 3.81 | 0.224 | 5.87% |
| 5 | 4.42 | 0.295 | 6.67% | 4.16 | 0.274 | 6.58% | 3.91 | 0.254 | 6.50% | 4.17 | 0.340 | 8.14% |
| 6 | 0.78 | 0.122 | 15.70% | 0.70 | 0.094 | 13.43% | 0.62 | 0.101 | 16.29% | 0.70 | 0.123 | 17.52% |
| 7 | 0.54 | 0.073 | 13.50% | 0.50 | 0.065 | 12.94% | 0.39 | 0.037 | 9.49% | 0.48 | 0.085 | 17.78% |
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Table 3
Linearity
| Serum | Neat | 1:2 | 1:4 | 1:8 | 1:16 | 1:32 | r |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 4.20 | 2.77 | 1.50 | 0.75 | | | 0.975 |
| 2 | 6.94 | 5.31 | 3.92 | 2.33 | 1.24 | 0.73 | 0.989 |
| 3 | 7.36 | 5.39 | 3.82 | 2.10 | 1.13 | 0.65 | 0.982 |
| 4 | 6.43 | 4.67 | 3.21 | 1.89 | 1.05 | 0.59 | 0.981 |
| 5 | 7.18 | 5.42 | 4.11 | 2.51 | 1.48 | 0.83 | 0.959 |
Linear regression compared dsDNA Index Value to $\log_2$ of dilution.
Table 4 Cross Reactivity
| Serum # | Index Value | Interpretation | Specificity |
| --- | --- | --- | --- |
| 1. | 0.28 | - | Ro |
| 2. | 0.52 | - | Ro |
| 3. | 0.74 | - | Ro |
| 4. | 0.53 | - | La |
| 5. | 0.28 | - | La |
| 6. | 0.70 | - | La |
| 7. | 0.64 | - | SM |
| 8. | 0.90 | equ | SM |
| 9. | 0.72 | - | SM |
| 10. | 0.58 | - | RNP |
| 11. | 0.40 | - | RNP |
| 12. | 0.82 | equ | RNP |
| 13. | 0.79 | - | SCL-70 |
| 14. | 0.70 | - | SCL-70 |
| 15. | 0.46 | - | SCL-70 |
| 16. | 0.25 | - | Jo-1 |
| 17. | 0.63 | - | Jo-1 |
| 18. | 0.76 | - | Jo-1 |
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Table 5 International Unit Conversion
| International Unit Standard Units / mL | Index Value |
| --- | --- |
| 200 | 4.20 |
| 100 | 2.37 |
| 50 | 1.50 |
| 25 | 0.75 |
Linear regression compared Index Value versus log International Units
r = 0.975 a = 0.25 b = 1.28 Y = log I.U. X = Index Value
Regression Equation Calculation
$Y = Xa + b \quad \text{I.U.} = 10^Y$
