← Product Code [CFN](/submissions/IM/subpart-f%E2%80%94immunological-test-systems/CFN) · K120749

# HUMAN IGG CSF KIT (K120749)

_The Binding Site Group , Ltd. · CFN · May 17, 2013 · Immunology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/CFN/K120749

## Device Facts

- **Applicant:** The Binding Site Group , Ltd.
- **Product Code:** [CFN](/submissions/IM/subpart-f%E2%80%94immunological-test-systems/CFN.md)
- **Decision Date:** May 17, 2013
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.5510
- **Device Class:** Class 2
- **Review Panel:** Immunology

## Intended Use

Human IqG CSF Kit for use on SPAPLUS is intended for the quantitative measurement of human IgG in cerebrospinal fluid (CSF) samples using the SPAPLUS analyser. Measurement of this immunoglobulin aids in the assessment of the body's lack of ability . to resist infectious disease in conjunction with other clinical and laboratory findings.

## Device Story

The Human IgG CSF Kit is an in vitro diagnostic assay designed for use on the SPAplus analyzer. It measures human IgG concentrations in cerebrospinal fluid (CSF) samples. The device utilizes immunoturbidimetric technology to quantify immunoglobulin levels. It is intended for use by laboratory professionals in clinical settings. The output provides quantitative IgG values, which clinicians use alongside other clinical and laboratory data to assess immune function and potential resistance to infectious diseases.

## Clinical Evidence

No clinical studies performed. Analytical performance established via bench testing: precision (CLSI EP05-A2), linearity (CLSI EP06-A), and method comparison against predicate (n=96, y=1.05x-0.27).

## Technological Characteristics

Turbidimetric assay; sheep anti-human IgG antibody; measuring range 4.2–135 mg/L. Reagents include antiserum, calibrators, and controls. Traceable to ERM-DA470k. Automated on SPAPLUS analyzer. Software performs automated concentration calculation based on calibration curve.

## Regulatory 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

- N Antisera to Human Immunoglobulin (IgG, IgA and IgM) (k083445)

## Submission Summary (Full Text)

> This content was OCRed from public FDA records by [Innolitics](https://innolitics.com). If you use, quote, summarize, crawl, or train on this content, cite Innolitics at https://innolitics.com.
>
> Innolitics is a medical-device software consultancy. We help companies design, build, and clear FDA-regulated software and AI/ML devices, including [a 510(k)](https://innolitics.com/services/510ks/), [a De Novo](https://innolitics.com/services/regulatory/), [a SaMD](https://innolitics.com/services/end-to-end-samd/), [an AI/ML medical device](https://innolitics.com/services/medical-imaging-ai-development/), or [an FDA regulatory strategy](https://innolitics.com/services/regulatory/).

{0}

1

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

A. 510(k) Number:
k120749

B. Purpose for Submission:
New Device

C. Measurand:
Immunoglobulin G

D. Type of Test:
Turbidimetry, Quantitative

E. Applicant:
The Binding Site Group, Ltd.

F. Proprietary and Established Names:
Human IgG CSF Kit for use on $\mathrm{SPA}_{\mathrm{PLUS}}$

G. Regulatory Information:

1. Regulation section:
21 CFR§866.5510 – Immunoglobulins A, G, M, D, and E immunological test system

2. Classification:
Class II

3. Product code:
CFN, Method, Nephelometric, Immunoglobulins (G, A, M)

4. Panel:
Immunology (82)

{1}

# H. Intended Use:

1. Intended use(s):

Human IgG CSF Kit for use on  $\mathrm{SPAPLUS}$  is intended for the quantitative measurement of human IgG in cerebrospinal fluid (CSF) samples using the  $\mathrm{SPAPLUS}$  analyzer. Measurement of this immunoglobulin aids in the assessment of the body's lack of ability to resist infectious disease in conjunction with other clinical and laboratory findings.

2. Indication(s) for use:

Same as Intended Use

3. Special conditions for use statement(s):

Prescription use only

4. Special instrument requirements:

$\mathrm{SPAPLUS}$  analyzer

# I. Device Description:

The kit contains the following materials:

Human IgG CSF Antiserum  $\mathrm{SPAPLUS}$  (1 x 60 tests), Liquid
Human IgG CSF  $\mathrm{SPAPLUS}$  Calibrator set 1-6 (6 x 1.0 mL), Lyophilized
CSF  $\mathrm{SPAPLUS}$  High Control  $(2\times 1.5\mathrm{mL})$  and Low Control  $(2\times 1.5\mathrm{mL})$
- Reaction Buffer (1 x 60 tests)

# J. Substantial Equivalence Information:

1. Predicate device name(s) and 510(K) number(s):

N Antisera to Human Immunoglobulin (IgG, IgA and IgM) (k083445)

2. Comparison with predicate:

|  Similarities and Differences  |   |   |
| --- | --- | --- |
|  Item | Device Human IgG CSF Kit for Use on SPAPLUS | Predicate N Antisera to Human Immunoglobulin (IgG, IgA and IgM)  |
|  Intended use | For the quantitative measurement of human IgG in cerebrospinal fluid (CSF) samples using the | For the quantitative measurement of immunoglobulins (IgG, IgA, and IgM) in human serum,  |

{2}

|  Similarities and Differences  |   |   |
| --- | --- | --- |
|  Item | Device
Human IgG CSF Kit for
Use on SPAPLUS | Predicate
N Antisera to Human
Immunoglobulin
(IgG, IgA and IgM)  |
|   | SPAPLUS analyzer.
Measurement of this
immunoglobulin aids in the
assessment of the body’s
lack of ability to resist
infectious disease in
conjunction with other
clinical and laboratory
findings. | heparinized and EDTA
plasma, and IgG in human
urine and cerebrospinal fluid
(CSF) by means of
nephelometry on the BN™
Systems. Measurements of
these immunoglobulins aids
in the diagnosis of abnormal
protein metabolism and the
body's lack of ability to
resist infectious agents  |
|  Analyte | Human IgG | Human IgG, IgA, and IgM  |
|  Sample type | CSF | Serum, heparinized and
EDTA plasma, human urine
and CSF  |
|  Method | Turbidimetry | Nephelometry  |
|  Instrument | SPAPLUS | BN system  |
|  Antibody | Sheep anti-human IgG | Rabbit anti-human IgG,
IgA, IgM  |
|  Measuring range | 4.2 – 135 mg/L
(at 1/1 sample dilution)

42 – 1350 mg/L
(at 1/10 sample dilution) | 3.6 – 115 mg/L  |
|  Stability | Open vial:
2 – 8°C for 2 months

On-board:
30 days | Open vial:
2 – 8°C for 4 weeks

On-board:
5 days with 8 hours/day  |
|  Reference range | <34 mg/L | Same  |

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

CLSI guideline EP05-A2 “Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline-Second Edition”.

CLSI guideline EP06-A “Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; Approved Guideline”.

## L. Test Principle:

The determination of soluble antigen concentration by turbidimetric methods involves the

{3}

reaction with specific antiserum to form insoluble complexes. When light is passed through the suspension formed a portion of the light is transmitted and focused onto a photodiode by an optical lens system. The amount of transmitted light is indirectly proportional to the specific protein concentration in the test samples. Concentrations are automatically calculated by reference to a calibration curve stored within the instrument.

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

# 1. Analytical performance:

# a. Precision/Reproducibility:

For CSF samples, the precision was evaluated based on CLSI EP05-A2 by testing three pooled samples with low (7.45 mg/L), mid (31.71 mg/L), and high (125.53 mg/L) IgG concentrations. The study was done over 5 days with 2 runs per day; each sample was run in duplicate within each run on one lot of reagent on one instrument due to the limited availability of CSF samples. The results are summarized in the following table:

|  Sample | Mean Conc. (mg/L) | Within-Run |   | Between-Run |   | Between-Day |   | Total  |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |   |  SD (mg/L) | CV % | SD (mg/L) | CV % | SD (mg/L) | CV % | SD (mg/L) | CV %  |
|  Low | 7.45 | 0.12 | 1.6 | 0.41 | 5.5 | 0.25 | 3.3 | 0.49 | 6.6  |
|  Mid | 31.71 | 0.27 | 0.9 | 1.58 | 5.0 | 2.04 | 6.4 | 2.59 | 8.2  |
|  High | 125.53 | 1.26 | 1.0 | 6.19 | 4.9 | 0 | 0 | 6.31 | 5.0  |

To supplement the CSF precision data, three pooled sera samples with low, mid, and high IgG concentration were assayed in duplicate with 2 runs per day for 21 days  $(n = 84)$  using three reagent lots and three instruments. Results are summarized below:

|  Sample | Mean Conc. (mg/L) | Within-Run |   | Between-Run |   | Between-Day |   | Total  |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |   |  SD (mg/L) | CV % | SD (mg/L) | CV % | SD (mg/L) | CV % | SD (mg/L) | CV %  |
|  Low | 6.00 | 0.21 | 3.5 | 0.65 | 7.8 | 0.26 | 4.3 | 0.73 | 8.3  |
|  Mid | 31.82 | 0.57 | 1.7 | 2.61 | 7.7 | 0 | 0 | 2.67 | 7.9  |
|  High | 101.54 | 2.24 | 2.0 | 1.60 | 1.4 | 2.27 | 2.0 | 3.56 | 3.2  |

# b. Linearity/assay reportable range:

Linearity: The linearity study was conducted based on CLSI EP06-A by analysis of a dilution series of pooled CSF sample. Each dilution was tested in triplicate. The observed values were graphed against the expected values and linear regression was performed. The results are summarized in the following table.

{4}

|  Sample range (mg/L) | Slope | Intercept | R² | % Recovery  |
| --- | --- | --- | --- | --- |
|  5.95 – 129.17 | 0.997 | -2.507 | 0.999 | 87.5 – 100.0  |
|  6.78 – 135.65 | 1.000 | -0.489 | 0.998 | 93.4 – 102.3  |
|  11.08 – 110.80 | 1.037 | -2.303 | 0.999 | 88.1 – 103.3  |
|  4.11 – 54.75 | 0.998 | -0.693 | 1.000 | 85.6 – 100.0  |

The claimed measuring range of the assay is  $4.2 - 135\mathrm{mg / L}$  (at 1/1 sample dilution).

Antigen excess (hook effect): The susceptibility of the assay to antigen excess was investigated. The results demonstrated that the assay is not susceptible to antigen excess up to a concentration of  $700\mathrm{mg / L}$ .

c. Traceability, Stability, Expected values (controls, calibrators, or methods):

Traceability: The calibrators, the internal reference standards (IR) and controls are traceable to reference standard ERM-DA470k. IR is used to control calibration between batches.

The table below summarizes the target values for calibrators and controls:

|   | Target Value (mg/L)  |
| --- | --- |
|  Calibrator  |   |
|  Calibrator 1 | 4.2  |
|  Calibrator 2 | 8.4  |
|  Calibrator 3 | 16.8  |
|  Calibrator 4 | 33.8  |
|  Calibrator 5 | 67.5  |
|  Calibrator 6 | 135  |
|  Controls  |   |
|  High Control | 85  |
|  Low Control | 30  |

# Stability:

Closed vial stability: The real time stability of IgG CSF kit was performed using three batches of kits stored under the recommended temperature at  $2 - 8^{\circ}\mathrm{C}$ . Data were collected at point 0, 3, 7, 10, 13, 19, and 25 months. The results support stability of the kits under the recommended storage of  $2 - 8^{\circ}\mathrm{C}$  for 24 months.

Open vial stability: The study was done to evaluate the reagent stability after first opening. Three batches of kits were stored at  $2 - 8^{\circ}\mathrm{C}$  after first opening. Data were collected at 1, 2, and 3 months. The results support that the reagents are stable once opened for up to 2 months when stored at  $2 - 8^{\circ}\mathrm{C}$ .

On-board stability: On-board stability of IgG CSF was done by placing the kit in the

{5}

reagent carousel of the $\mathrm{SPA}_{\mathrm{PLUS}}$. The reagent carousel was covered and cooled to $8 - 12^{\circ}\mathrm{C}$. A calibration curve was generated on Day 0 and validated with the IgG CSF kit controls. The test data were collected at Day 0, Day 14, and Day 35. The result supports that the reagents are stable up to 30 days on-board the $\mathrm{SPA}_{\mathrm{PLUS}}$.

d. Detection limit:

The limit of blank (LoB) for this assay was determined by testing instrument diluent. The limit of detection (LoD) was determined by testing CFS sample with low IgG concentration. Sixty (60) replicates of each sample were run, and the mean and standard deviation for each of the samples was calculated. $\mathrm{LoD} = \mathrm{LoB} + 1.645 \times \mathrm{SDs}$ where SDs is the standard deviation of the replicate samples. The LoQ was tested using the lowest calibrator fluid with assigned concentration $3.802\mathrm{mg / L}$. The claimed LoB, LoD and LoQ are summarized in the following table:

|  LoB | LoD | LoQ  |
| --- | --- | --- |
|  0 mg/L | 0.6925 mg/L | 4.4601 mg/L  |

e. Analytical specificity:

**Endogenous interference**: Interference by endogenous substances was evaluated by using one CSF sample base pool at the medical decision point (34 mg/L) spiked with hemoglobin and bilirubin. The negative samples were prepared by spiking the same volume of commercially obtained blank reagents into the CSF pool. The resulting samples were tested in triplicate and the mean values were used to calculate % interference. No significant interference was noted for sample containing hemoglobin at 2.5 g/L and bilirubin at 100 mg/L.

**Drug interference**: Interference by drugs was evaluated by using one CSF sample base pool (at concentration of $34\mathrm{mg / L}$) spiked with acetaminophen and aspirin dissolved in distilled water. The negative samples were prepared by spiking the CSF pool with the same volume of distilled water. All samples were tested in triplicate and the mean values were used to calculate % interference. No significant interference was observed for sample containing acetaminophen at $200\mathrm{mg / L}$ and aspirin at $600\mathrm{mg / L}$.

**Bacterial interference**: No bacterial interference study was performed. In the labeling, the following statement is added in section of Limitations of the package insert:

"Bacterial interference has not been assessed. CSF samples should be as fresh as possible to limit bacterial growth and all samples must be centrifuged prior to testing (see section 7)".

f. Assay cut-off:

The cut-off is the same as the predicate and is defined as the upper limit of the

{6}

reference range (established from literature). The reference range for IgG in CSF is $&lt; 34\mathrm{mg / L}$

## 2. Comparison studies:

a. Method comparison with predicate device:

A method comparison study was performed to compare the IgG CSF kit on $\mathrm{SPA}_{\mathrm{PLUS}}$ (y) and the predicate device on Siemens BNII system (x) using CSF samples. Total 96 samples including normal and clinical CSF samples were tested. 27 out of 96 samples were spiked with IgG in order to fully span the measuring range for both proposed and predicate devices. The results were summarized as follows:

|  N= | Sample range (mg/L) | Comparison (Passing/Bablok)  |
| --- | --- | --- |
|  96 | 4.39 – 114.00 | y =1.05x – 0.27
Slope (95% CI): 1.02 – 1.08
Intercept (95% CI): -1.51 – 0.90  |

b. Matrix comparison:

Not applicable, assay use CSF sample only

## 3. Clinical studies:

a. Clinical Sensitivity:

Not applicable

b. Clinical specificity:

Not applicable

c. Other clinical supportive data (when a. and b. are not applicable):

Not applicable

## 4. Clinical cut-off:

See assay cut-off

## 5. Expected values/Reference range:

The reference range for IgG in CSF is $&lt; 34\mathrm{mg / L}$ according to the literature. It is strongly recommended that each facility should determine its own reference intervals. The reference values in the true sense only exist to the CSF/serum ratio.

7

{7}

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.

8

---

**Source:** [https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/CFN/K120749](https://fda.innolitics.com/submissions/IM/subpart-f%E2%80%94immunological-test-systems/CFN/K120749)

**Published by [Innolitics](https://innolitics.com)** — a medical-device software consultancy. We help companies design, build, and clear FDA-regulated software and AI/ML devices. If you're preparing [a 510(k)](https://innolitics.com/services/510ks/), [a De Novo](https://innolitics.com/services/regulatory/), [a SaMD](https://innolitics.com/services/end-to-end-samd/), [an AI/ML medical device](https://innolitics.com/services/medical-imaging-ai-development/), or [an FDA regulatory strategy](https://innolitics.com/services/regulatory/), [get in touch](https://innolitics.com/contact).

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