HUMAN IGG SUBCLASS LIQUID REAGENT KITS FOR USE ON THE SPAPLUS ANALYSER
Device Facts
| Record ID | K072889 |
|---|---|
| Device Name | HUMAN IGG SUBCLASS LIQUID REAGENT KITS FOR USE ON THE SPAPLUS ANALYSER |
| Applicant | The Binding Site, Ltd. |
| Product Code | CFN · Immunology |
| Decision Date | Feb 1, 2008 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 866.5510 |
| Device Class | Class 2 |
Intended Use
This kit is intended for quantifying human IgG and IgG subclasses 1, 2, 3, and 4 immunoglobulins in serum using the SPA PLUS Analyzer. Measurement of these immunoglobulins aids in the diagnosis of abnormal protein metabolism and the body’s lack of ability to resist infectious agents.
Device Story
The device consists of liquid reagents, including polyclonal monospecific sheep antisera (for IgG1, IgG2, and total IgG) and latex-coated polyclonal monospecific sheep antisera (for IgG3 and IgG4), used on the SPA PLUS Analyzer. The system employs nephelometry to measure light scattered by insoluble immune complexes formed between the sample antigen and the specific antibody. For reactions with insufficient complex size, latex-enhanced particles are used to increase light scattering. The analyzer automatically calculates concentrations by referencing a stored standard curve. The device is intended for use in clinical laboratory settings by trained personnel. Results assist healthcare providers in diagnosing protein metabolism disorders and immune deficiencies. The system provides quantitative measurements of IgG and its subclasses, facilitating clinical assessment of a patient's ability to resist infectious agents.
Clinical Evidence
Bench testing only. Precision was evaluated per CLSI EP5-A over 21 days, meeting ±15% acceptance criteria. Linearity was confirmed across reportable ranges (r² > 0.99). Method comparison with predicate devices using 60 clinical samples showed strong correlation (R² > 0.97). Interference testing showed no significant impact from bilirubin, hemoglobin, or chyle (up to 1670 FTU). Reference ranges were established using 120 normal sera for IgG and 30 for subclasses.
Technological Characteristics
Semi-quantitative nephelometric assay. Reagents: Polyclonal monospecific sheep antisera (liquid) and latex-enhanced sheep antisera. Detection: Light scattering proportional to antigen concentration. Calibration: Six-point curve, traceable to CRM470 International Reference Material. Instrument: SPA PLUS Analyzer. Standards: CLSI EP5-A for precision. Storage: 2-8°C.
Indications for Use
Indicated for the quantification of human IgG and IgG subclasses 1, 2, 3, and 4 in serum to aid in the diagnosis of abnormal protein metabolism and immune deficiency. For prescription use only.
Regulatory Classification
Identification
An immunoglobulins A, G, M, D, and E immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the immunoglobulins A, G, M, D, an E (serum antibodies) in serum. Measurement of these immunoglobulins aids in the diagnosis of abnormal protein metabolism and the body's lack of ability to resist infectious agents.
Predicate Devices
- Binding Site Human IgG Subclass kit for use on the Behring II Analyzer (k012292)
- Dade Behring N Antisera to Human Immunoglobulins (k042735)
Submission Summary (Full Text)
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
A. 510(k) Number:
k072889
B. Purpose for Submission:
New submission
C. Measurand:
IgG and IgG subclasses 1, 2, 3, and 4
D. Type of Test:
Semi-quantitative Nephelometry
E. Applicant:
The Binding Site, Ltd.
F. Proprietary and Established Names:
Binding Site Human IgG and IgG Subclass Liquid Reagent Kits for use on the
SPA PLUS Analyzer
G. Regulatory Information:
1. Regulation section:
21 CFR 866.5510, Immunoglobulins A, G, M, D, E Immunological Test Systems
2. Classification:
Class II
3. Product code:
CFN, Method, Nephelometric, Immunoglobulins (G,A,M)
4. Panel:
Immunology 82
H. Intended Use:
1. Intended use(s):
This kit is intended for quantifying human IgG and IgG subclasses 1, 2, 3, and 4
immunoglobulins in serum using the SPA PLUS Analyzer. Measurement of these
immunoglobulins aids in the diagnosis of abnormal protein metabolism and the
body’s lack of ability to resist infectious agents.
2. Indication(s) for use:
Same as Intended Use
3. Special conditions for use statement(s):
For prescription use only
4. Special instrument requirements:
SPA PLUS Analyzer (k062372)
I. Device Description:
The device consists of these reagents: Polyclonal monospecific sheep antisera in
liquid form for IgG1 and IgG2; polystyrene latex coated with polyclonal
monospecific sheep antisera for IgG3 and IgG4; total IgG antiserum in liquid form;
Calibrators 1-6; Low and High controls (pooled human sera) in liquid form; and
supplementary reagent.
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J. Substantial Equivalence Information:
1. Predicate device name(s):
Binding Site Human IgG Subclass kit for use on the Behring II Analyzer
Dade Behring N Antisera to Human Immunoglobulins
2. Predicate K number(s):
k012292 (IgG subclass)
k042735 (IgG)
3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicates |
| Intended Use | Aid in the diagnosis of abnormal protein metabolism and the body’s lack of ability to resist infectious agents. | Same |
| Number of calibrators | Six | Same |
| Detection Method | Nephelometry | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Sample Matrix | Serum | Serum, plasma, urine and CSF |
| Instrument | The Binding Site SPAPLUS™ | Dade Behring II Analyzer |
K. Standard/Guidance Document Referenced (if applicable):
CLSI document EP5-A: Evaluation of Precision Performance of Clinical Chemistry;
L. Test Principle:
Nephelometry involves the measurement of light scattered by particles in solution. This can be applied to the measurement of soluble antigen since, in the presence of the appropriate antibody, insoluble immune complexes are formed, which are light scattering. When the antibody is in excess, the light scatter is directly proportional to the concentration of antigen. Concentrations are automatically calculated by reference to a standard curve stored within the instrument.
Latex-enhanced Antibodies: Some antibody-antigen reactions do not form sufficiently large immune complexes to be detected nephelometrically. If the antibody is coated onto latex particles of a suitable size, the light scattering ability of the immune complexes formed with antigen is enhanced sufficiently to enable turbidimetric detection.
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# M. Performance Characteristics (if/when applicable):
# 1. Analytical performance:
# a. Precision/Reproducibility:
A precision study was performed according to CLSI document EP5-A: Evaluation of Precision Performance of Clinical Chemistry Approved Guideline. Three different serum samples representing the low, medium and high levels of the measuring range were tested over 21 days, 2 runs per day, in duplicate. One user assessed three different samples using three different lots. Acceptance criteria $\pm 15\%$ were met
| IgG | | Within run | | Between-run | | Between-day | | Total Precision | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Level | Mean (g/L) | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low | 2.43 | 0.05 | 2.1 | 0.03 | 1.4 | 0.18 | 7.6 | 0.19 | 8.0 |
| Medium | 6.0 | 0.09 | 1.5 | 0.07 | 1.1 | 0.29 | 4.8 | 0.31 | 5.1 |
| High | 33.0 | 0.81 | 2.5 | 0.0 | 0.0 | 0.61 | 1.91 | 1.02 | 3.1 |
| IgG 1 | | Within run | | Between-run | | Between-day | | Total Precision | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Level | Mean (g/L) | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low | 2.55 | 0.05 | 2.1 | 0.08 | 3.2 | 0.22 | 8.7 | 0.24 | 9.5 |
| Medium | 3.83 | 0.10 | 2.7 | 0.09 | 2.3 | 0.30 | 7.8 | 0.33 | 8.5 |
| High | 31.86 | 0.70 | 2.2 | 0.46 | 1.5 | 1.65 | 5.3 | 1.85 | 5.9 |
| IgG 2 | | Within run | | Between-run | | Between-day | | Total Precision | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Level | Mean (g/L) | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low | 0.245 | 0.01 | 3.6 | 0.02 | 7.3 | 0.01 | 4.9 | 0.02 | 9.6 |
| Medium | 2.349 | 0.06 | 2.4 | 0.07 | 3.0 | 0.07 | 3.1 | 0.12 | 4.9 |
| High | 4.145 | 0.03 | 0.8 | 015 | 3.5 | 0.07 | 1.6 | 0.16 | 3.9 |
| IgG 3 | | Within run | | Between-run | | Between-day | | Total Precision | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Level | Mean (g/L) | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low | 0.081 | 0.0 | 2.8 | 0.00 | 2.8 | 0.01 | 8.3 | 0.01 | 9.2 |
| Medium | 0.227 | 0.01 | 3.3 | 0.00 | 0.0 | 0.01 | 3.8 | 0.01 | 5.1 |
| High | 0.844 | 0.03 | 3.3 | 0.00 | 0.0 | 0.03 | 3.3 | 0.04 | 4.6 |
| IgG 4 | | Within run | | Between-run | | Between-day | | Total Precision | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Level | Mean (g/L) | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low | 0.049 | 0.0 | 5.3 | 0.00 | 0.0 | 0.00 | 8.3 | 0.00 | 9.8 |
| Medium | 0.066 | 0.0 | 4.0 | 0.00 | 2.3 | 0.01 | 7.8 | 0.01 | 9.0 |
| High | 0.769 | 0.01 | 1.9 | 0.01 | 0.9 | 0.04 | 5.1 | 0.04 | 5.5 |
# b. Linearity/assay reportable range:
Three serum samples previously identified as containing high levels of IgG and IgG subclasses were serially diluted (off-line dilution, 1:2 to 1:128) and each dilution assayed using the $\mathrm{SPA}_{\mathrm{PLUS}}$ , using three different lots. The assays
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were run at the normal sample dilutions 1/10 and 1/1 (neat) to cover the measuring ranges as follows:
IgG 1.65 - 35.0 g/L
IgG1 1.50 - 36.0 g/L
IgG2 0.20 - 5.5 g/L
IgG3 0.055 - 1.00 g/L
IgG4 0.03 - 0.85 g/L
Each dilution was analyzed in duplicate. Linear regression analyses were performed comparing the actual results versus the calculated values. The following equations were obtained:
IgG y=1.0082x - 0.0784, r²=0.9970
IgG1 y=0.9945x - 0.2107, r²=0.9992
IgG2 y=1.0091x -0.0046, r²=0.9996
IgG3 y=1.0076x - 0.001, r²=0.9998
IgG4 y=0.9993x - 0.0005, r² = 1.00
Data confirms the linearity of the assay over the reportable measuring ranges.
c. Traceability, Stability, Expected values (controls, calibrators, or methods): Calibrator and corresponding control sera are sourced from different pools of sera. Calibrator and control value assignment is controlled during kit production using set target values for the initial fluid of pooled human serum. An internal reference standard (IR7955) was assigned by comparison with the CRM470 International Reference Material. Values of 10.081 g/L for IgG, 5.3691 g/L for IgG1, 3.597 g/L for IgG2, 0.464 g/L for IgG3 and 0.334 g/L for IgG4 were obtained. This IR was then used to validate curves and standardize kit calibration.
To demonstrate the stability of the Binding site's (TBS) IgG and IgG subclass 1-4 assays on the SPAPLUS Analyzer, three kit lots of IgG and each of the 4 IgG subclasses were tested according to the product insert. The first assays were run following 1 week of storage at 22°C for 1 week to simulate shipping conditions. The kits were tested at Time 0 and at 3 and 7 months. The kits were stored at recommended temperature of 2-8°C. At each stage a calibration curve was run together with the two kit controls and an internal reference (IR) standard.
The results obtained demonstrate that the IgG and IgG subclass 1-4 kits are stable for at least 7 months from the date of manufacture when stored at the recommended storage temperature of 2-8°C.
d. Detection limit:
Limit of blank was determined as the mean concentration + 2 SD given by 20 determinations of the sample diluent and results are summarized below:
IgG 0.165 g/L
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IgG1 0.150 g/L
IgG2 0.02 g/L
IgG3 0.0055 g/L
IgG4 0.003 g/L
e. Analytical specificity:
Susceptibility to interference was assessed by adding high concentrations of bilirubin, hemoglobin and chyle to test serum samples which contained a known concentration of IgG, IgG1, IgG2, IgG3, and IgG4. The test samples consisted of the respective low kit controls, which were diluted with saline. Percentage interference was calculated from comparison with (serum + saline) blank. Deviations less than or equal to ±10% of the blank value were considered to show no significant interference. Results demonstrated
- No significant assay interference by 200 mg/L bilirubin or 5 g/L hemoglobin.
- No significant assay interference by 4395 formazine turbidity units (FTU) of chyle IgG1, IgG3 and IgG4.
- Slight assay interference (15%) with chyle (2210 FTU) but no significant interference was noted with chyle at 1670 FTU for IgG2.
f. Assay cut-off:
Not provided.
2. Comparison studies:
a. Method comparison with predicate device:
The IgG assay was compared to the Dade Behring assay (k042735) and the IgG subclass assays were compared to TBS IgG subclass BN assays (k012292). For these studies, 60 sera (30 normal and 30 clinical samples with elevated levels of IgG/IgG1-4) were tested. The following summation data were provided:
IgG: y = 1.0779x - 0.9028 R² = 0.9787
IgG1: y = 1.0437x - 0.1612 R² = 0.9850
IgG2: y = 1.059x - 0.1619 R² = 0.9874
IgG3: y = 1.0062x - 0.0082 R² = 0.97831
IgG4: y = 0.9897x - 0.0052 R² = 0.9959
Additional ten samples were assayed to cover the low end of the measuring ranges with the following results:
IgG: y = 0.932x + 0.0433 R² = 0.9844
IgG1: y = 0.9145x - 0.0546 R² = 0.9985
IgG2: y = 0.9972x - 0.167 R² = 0.9883
IgG3: y = 0.948x - 0.0015 R² = 0.9944
IgG4: y = 0.9237x - 0.0501 R² = 0.9987
b. Matrix comparison:
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Serum is the only recommended sample for this assay.
3. Clinical studies:
a. Clinical Sensitivity: None provided.
b. Clinical specificity: None provided.
c. Other clinical supportive data (when a. and b. are not applicable): Not applicable.
4. Clinical cut-off: Not provided
5. Expected values/Reference range:
Adult normal range was assessed using 120 normal sera for IgG and 30 normal sera for the subclasses obtained from healthy adult blood donors. All samples were stored at -20°C prior to the assay. A non-parametric distribution of IgG results was seen that gave a 95 percentile reference interval of 6.103-16.16 g/L with a mean of 10.926 g/L. These results are very similar to that of the predicate device (Dade Behring).
| IgG Subclass | Number (n) | Mean (g/L) | Median (g/L) | 95^{th} Percentile range (g/L) |
| --- | --- | --- | --- | --- |
| Total IgG | 120 | 10.926 | 10.807 | 6.103-16.16 |
| IgG1 | 30 | 6.33 | 6.085 | 3.824-9.286 |
| IgG2 | 30 | 4.528 | 4.541 | 2.418-7.003 |
| IgG3 | 30 | 0.7907 | 0.7064 | 0.2182-1.7606 |
| IgG4 | 30 | 0.28 | 0.2153 | 0.0392-0.864 |
Pediatric normal ranges shown in the package insert (section 11.2) were obtained using Binding Site radial immunodiffusion (RID) assay. In order to justify the inclusion of pediatric data and to demonstrate correlation between RID and the Binding Site Human IgG Subclass Liquid Reagent Kits for use on the SPAPLUS Analyzer, 14 panel samples were tested and the following results were obtained:
IgG: $y = 1.1112x - 1.3378$ $R^2 = 0.9932$
IgG1: $y = 0.9898x - 0.1586$ $R^2 = 0.9828$
IgG2: $y = 0.9094x - 0.0039$ $R^2 = 0.9489$
IgG3: $y = 1.2158x - 0.1089$ $R^2 = 0.9489$
IgG4: $y = 0.8967x - 0.0123$ $R^2 = 0.9832$
N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
O. Conclusion:
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The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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