← Product Code [NST](/submissions/IM/subpart-f%E2%80%94immunological-test-systems/NST) · K051144

# ACETYLCHOLINE RECEPTOR AB (ARAB)RRA (K051144)

_Ibl-Hamburg GmbH · NST · Nov 18, 2005 · Immunology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/NST/K051144

## Device Facts

- **Applicant:** Ibl-Hamburg GmbH
- **Product Code:** [NST](/submissions/IM/subpart-f%E2%80%94immunological-test-systems/NST.md)
- **Decision Date:** Nov 18, 2005
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.5660
- **Device Class:** Class 2
- **Review Panel:** Immunology

## Indications for Use

The IBL Acetylcholine Receptor Antibody (ARAb) Radio Receptor Assay is for the in-vitrodiagnostic semi-quantitative determination of autoantibodies against the acetylcholine receptor in human serum and plasma. The ARAb Assay kit is useful as an aid in the differential diagnosis of Myasthenia Gravis (MG).

## Device Story

In-vitro diagnostic radio receptor assay (RRA) for detection of acetylcholine receptor autoantibodies in human serum or plasma; aids in differential diagnosis of Myasthenia Gravis. Laboratory-based test; performed by trained technicians. Principle involves competitive binding; patient autoantibodies compete with labeled ligands for receptor sites. Output is semi-quantitative measurement of antibody levels. Results interpreted by clinicians to support clinical diagnosis of MG.

## Clinical Evidence

No clinical data provided in the document; substantial equivalence determination based on bench testing and performance characteristics of the radio receptor assay.

## Technological Characteristics

Radioreceptor immunoassay. Components: I125-labeled acetylcholine receptors, anti-human IgG antiserum, calibrators, wash buffer (PBS/Triton X100). Detection: Gamma counter. Matrix: Serum and plasma. Connectivity: Standalone. Software: None (manual calculation of standard curve).

## Regulatory 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).

## Submission Summary (Full Text)

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>
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

A. 510(k) Number:
K051144

B. Purpose for Submission:
New device.

C. Measurand:
Acetylcholine receptor autoantibodies.

D. Type of Test:
Semi-quantitative, Radio receptor assay

E. Applicant:
IBL-Hamburg GmbH

F. Proprietary and Established Names:
Acetylcholine Receptor Ab (ARAb) RRA

G. Regulatory Information:
1. Regulation section:
21 CFR § 866.5660, Multiple Autoantibodies Immunological Test System
2. Classification:
Class II
3. Product code:
NST, Autoantibodies, Acetylcholine Receptor, Acetylcholine Blocking and Non-Blocking.
4. Panel:
Immunology (82)

H. Intended Use:
1. Intended use(s):
The IBL Acetylcholine Receptor Antibody (ARAb) Radio Receptor Assay is for semi-quantitative determination of autoantibodies against the acetylcholine receptor in human serum and plasma. The ARAb assay kit is useful as an aid in the differential diagnosis of Myasthenia Gravis (MG).
2. Indication(s) for use:
Same as intended use.
3. Special conditions for use statement(s):
The device is for prescription use only.
4. Special instrument requirements:
Gamma counter for I¹²⁵.

I. Device Description:
The IBL Acetylcholine Receptor Antibody (ARAb) Assay Kit consists of:
1. Lyophilized I¹²⁵ Acetylcholine Receptor from human muscle and labeled with I¹²⁵ alpha-bungarotoxin.
2. I¹²⁵ ARAb Tracer (lyophilized)
3. IgG Antiserum contains anti-human IgG, 0.1% NaN₃, ready-to-use.
4. Positive control contains human serum, antibodies to acetylcholine receptors-ready to use.

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5. Standard A-F 0; 0.2; 0.5; 1.2; 3.0; 8.0nmol/L- ready to use.

Standard A = sample diluent- normal human serum

6. Positive control, ready-to-use.
7. Wash buffer -PBS with  $0.01\%$  Triton X100.  $0.1\%$ $\mathrm{NaN}_3$ - ready to use.
8. Buffer for reconstitution of tracer, contains PBS,0.5 Triton and  $0.005\%$ $\mathrm{NaN}_3$

# J. Substantial Equivalence Information:

The sponsor claimed the new device is substantially equivalent to the Kronus Acetylcholine Receptor antibody Kit. The intended use and indications for use and methodology are the same. There is clinical data to support the claim.

1. Predicate device name(s):

Kronus  $\mathrm{I}^{125}$  Acetylcholine Receptor Antibody Kit

2. Predicate 510(k) number(s):

k042248

3. Comparison with predicate:

|  Similarities  |   |   |
| --- | --- | --- |
|  Item | Predicate | New device  |
|  Device Name | Kronus Acetylcholine Receptor Antibody (AChRAb) Assay Kit | IBL Acetylcholine receptor antibody assay (ARAb RRA)  |
|  Intended use | Detection of autoantibodies to specific receptor | Same  |
|  Test Principle | Radioreceptor immunoassay | Same  |
|  Test matrix | Serum | Serum and plasma  |
|  Test Platform | Receptors bind to serum antibodies in a liquid phase (test tube), the antibody-antigen complexes are precipitated and radioactivity measured | Same  |
|  Detection instrument | Gamma counter | Same  |
|  Differences  |   |   |
|  Expected values | Serum< 0.2nmol/L | Serum0.029 ± 0.018 nmol/L Plasma 0.023± 0.013 nmol/L  |
|  Negative/cut-off | ≤ 0.2nmol/L | < 0.25 nmol/L  |
|  Equivocal | 0.21-049 nmol/L | 0.25-0.4 nmol/L  |
|  Positive | ≥ 0.5 nmol/L | > 0.4 nmol/L  |
|  Detection limit | 0.26 nmol/L | 0.01nmol/L  |
|  Assay range | 0.3-7.0 nmol/L | 0.25-1.5 nmol/L  |

# K. Standard/Guidance Document Referenced (if applicable):

None referenced.

# L. Test Principle:

Patient specimens and reference reagents are incubated at  $18 - 25^{\circ}\mathrm{C}$  for 2 hours with adult acetylcholine receptors (ARAb) labeled with  $\mathrm{I}^{125}$  -alpha-bungarotoxin. The

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resulting bound complexes of labeled ARAb and autoantibody are then immunoprecipitated with anti-human IgG. After centrifugation, the supernatant is aspirated and the pellet containing labeled ARAb/autoantibody-bound complex is counted in a gamma counter for 1 min. Counts are directly proportional to the amount of autoantibody present and results are expressed as the concentration of alpha-bungarotoxin bound (nmoles/L toxin bound). A standard curve is generated to calculate the values. All samples with a mean cpm above the cut off are considered positive.

## M. Performance Characteristics (if/when applicable):

### 1. Analytical performance:

#### a. Precision/Reproducibility:

Intra-assay precision was determined by analyzing 22 replicates of 7 control samples. The following table summarizes the results.

|  Sample | N | Mean ARAb (nmol/L) | SD (nmol/L) | % CV  |
| --- | --- | --- | --- | --- |
|  1 | 22 | 0.19 | 0.01 | 5.1  |
|  2 | 22 | 0.41 | 0.01 | 3.1  |
|  3 | 22 | 0.75 | 0.02 | 2.8  |
|  4 | 22 | 1.55 | 0.06 | 3.8  |
|  5 | 22 | 2.62 | 0.17 | 6.3  |
|  6 | 22 | 4.57 | 0.39 | 8.5  |
|  7 | 22 | 5.72 | 0.65 | 11.3  |

Inter-assay variation was assessed by analyzing 7 samples and 15 assay runs. The assays were performed in different labs with 3 different technicians using one kit lot. The mean coefficient of variation was found to be 70% (range 2.8-13.1%). Results are shown in the table below.

|  Serum sample | Mean (nmol/L) | SD | CV % | N  |
| --- | --- | --- | --- | --- |
|  1 | 0.21 | 0.01 | 5.3 | 14  |
|  2 | 0.40 | 0.01 | 2.8 | 15  |
|  3 | 0.75 | 0.02 | 3.0 | 15  |
|  4 | 1.61 | 0.07 | 4.3 | 15  |
|  5 | 2.63 | 0.20 | 7.7 | 15  |
|  6 | 4.72 | 0.59 | 12.4 | 15  |
|  7 | 6.10 | 0.80 | 13.1 | 15  |

#### b. Linearity/assay reportable range:

Four serum samples with different acetylcholine receptor antibody levels were diluted with Zero calibrator and Acetylcholine receptor antibody content, in ratios 1:2, 1:4, 1:8, 1:16, 1:32 and 1:64

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|  Sample | Dilution | Measured (nmol/L) | Recovery (%) | Sample | Dilution | Measured (nmol/L) | Recovery (%)  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  1 | - | 7.038 | 100 | 3 | - | 2.711 | 100  |
|   |  1:2 | 3.927 | 112 |   | 1:2 | 1.164 | 86  |
|   |  ! : 4 | 1: 833 | 104 |   | 1:4 | 0.565 | 83  |
|   |  1:8 | 0.924 | 105 |   | 1:8 | 0.263 | 78  |
|   |  1:16 | 0.467 | 106 |   | 1:16 | 0.134 | 79  |
|   |  1:32 | 0. 219 | 100 |   | 1:32 | 0.076 | 90  |
|   |  1:64 | 0. 122 | 111 |   | 1:6 | 0.057 | 135  |
|  2 | - | 4.926 | 100 | 4 | - | 1.624 | 100  |
|   |  1:2 | 2.568 | 104 |   | 1:2 | 0.808 | 100  |
|   |  1:4 | 1.200 | 97 |   | 1:4 | 0.416 | 102  |
|   |  1:8 | 0.553 | 90 |   | 1:8 | 0.205 | 101  |
|   |  1:16 | 0.269 | 87 |   | 1:16 | 0.108 | 106  |
|   |  1:32 | 0.124 | 81 |   | 1:32 | 0.048 | 95  |
|   |  1:64 | 0.075 | 97 |   | 1:64 | 0.032 | 126  |

Recovery: Increasing amounts of acetylcholine receptor antibodies were added to serum samples with various initial acetylcholine receptor antibody concentrations. Each sample was assayed in duplicate in one run. % recovery rates were calculated. Mean recovery was 106% ± 19% (range 87-153%).

|  Sample | Endogenous ARAb (nmol/L) | Added ARAb (nmol/L) | Measured ARAb (nmol/L) | Recovery (%)  |
| --- | --- | --- | --- | --- |
|  1 | 00 | 0.22 | 0.20 | 91  |
|   |  00 | 0.60 | 0.52 | 87  |
|   |  00 | 1.80 | 2.11 | 117  |
|  2 | 0.21 | 0.22 | 0.43 | 100  |
|   |  0.21 | 0.60 | 0.87 | 107  |
|   |  0.21 | 1.80 | 3.07 | 153  |
|  3 | 0.48 | 0..22 | 0.66 | 94  |
|   |  0.48 | 0.60 | 0.97 | 90  |
|   |  0.48 | 1.80 | 2.53 | 111  |

c. Traceability, Stability, Expected values (controls, calibrators, or methods): No reference material available.

d. Detection limit: The lower detection limit is 0.01nmol/L.

e. Analytical specificity: Cross reactivity with autoantibodies potentially interfering with ARAb RRA was assessed. Nine patient serum samples containing autoantibodies (anti-Sm, -RNP, -RO (SSA), La (SS-B), -dsDNA, -RF, and ANA) were tested. No cross reactivities were found with any of the antibodies. In addition, hemoglobin (0.25 and 4 mg/mL), bilirubin (0.03 and 0.5 mg/mL and triglycerides (0.2 to 30mg/mL) were evaluated for interference. All test

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results are available in the submission. Results showed no significant interference at the concentrations tested.

f. Assay cut-off:
One hundred and thirty serum and EDTA plasma samples from blood donors were assayed. Range of values were between 0.013 and 0.116 nmol/L for serum and 0.013 and 0.086 nmol/L for plasma. The upper limit of reference range is at 0.110 nmol/L for serum and 0.081 nmol/L for plasma. Cut off is set at 0.25 nmol/L. Antibody titers greater than 0.4 nmol/L are indicative of Myasthenia Gravis (positive). Values between 0.25 and 0.4 nmol/L is considered as equivocal

2. Comparison studies:

a. Method comparison with predicate device:
Fifty-three patient samples consisted of 38 Myasthenia Gravis positive samples and 15 Myasthenia Gravis negative samples were tested with the Kronus RIA test and IBL RRA test. Equivocal results are considered positive. Comparative results are summarized below:

|   | KRONUS  |   |   |   |   |
| --- | --- | --- | --- | --- | --- |
|   |   |  + | Equivocal | - | Total  |
|  IBL | + | 37 | 0 | 0 | 37  |
|   |  Equivocal | 2 | 0 | 0 | 2  |
|   |  - | 0 | 2 | 12 | 14  |
|   |  Total | 39 | 2 | 12 | 53  |

% Positive agreement = 95.1% (39/41) (95% CI: 83.5% to 99.4%)
% Negative agreement = 100% (12/12) (95% CI: 73.5% to 100%)
% Total agreement = 96.2% (51/53)

b. Matrix comparison:
Seven patient samples, serum and EDTA plasma, comparison showed no significant difference. A correlation coefficient of linear regression was r = 0.984. Regression line was calculated (plasma) = 0.931 (serum) + 0.062.

3. Clinical studies:

a. Clinical sensitivity and specificity:
The same samples used in the comparison study were also used to determine the clinical sensitivity and specificity of the IBL RRA and the Kronus RIA. Results are shown in tables below.

|   | Myasthenia Gravis |   |   |   |
| --- | --- | --- | --- | --- |
|   |   |  + | - | Total  |
|  IBL | + | 38 | 1 | 39  |
|   |  - | 0 | 14 | 14  |
|   |  Total | 38 | 15 | 53  |

Sensitivity = 100% (95% CI: 90.8% to 100%)
Specificity = 93.3% (95% CI: 68.1% to 99.8%)

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|   | Myasthenia Gravis |   |   |   |
| --- | --- | --- | --- | --- |
|   |   |  + | - | Total  |
|  Kronus | + | 38 | 3 | 41  |
|   |  - | 0 | 12 | 12  |
|   |  Total | 38 | 15 | 53  |

Sensitivity = 100% (95% CI: 90.8 to 100%)

Specificity = 80% (95% CI: 51.9% to 95.7%)

b. Other clinical supportive data (when a is not applicable):

Not applicable.

4. Clinical cut-off:

See Assay cut-off.

5. Expected values/Reference range:

The expected value in normal population is less than 0.013 nmol/L.

N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

O. Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

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**Source:** [https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/NST/K051144](https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/NST/K051144)

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**Cite:** Innolitics at https://innolitics.com