RIBOSOMAL P EIA TEST SYSTEM

K950169 · Hogan & Hartson · MQA · May 23, 1996 · Immunology

Device Facts

• Record ID: K950169
• Device Name: RIBOSOMAL P EIA TEST SYSTEM
• Applicant: Hogan & Hartson
• Product Code: MQA · Immunology
• Decision Date: May 23, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.5100
• Device Class: Class 2

Intended Use

The Ribosomal P ELISA test is an enzyme-linked immunosorbent assay (ELISA) for the detection and semi-quantitation of IgG antibodies to Ribosomal P in human sera. The assay is to be used to detect 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). FOR IN VITRO DIAGNOSTIC USE.

Device Story

Ribosomal P ELISA test kit detects IgG antibodies to Ribosomal P in human serum. Purified Ribosomal P antigen is immobilized on microtiter wells; patient serum is added; antibodies bind to antigen. After washing, enzyme-labeled anti-human IgG is added; substrate solution induces color change proportional to antibody concentration. Color intensity measured photometrically. Used in clinical laboratory settings by trained personnel. Output provides semi-quantitative index values to aid SLE diagnosis.

Clinical Evidence

Bench testing and clinical cohort study. Sensitivity/specificity evaluated against Ouchterlony analysis (n=183: 46 positive, 137 negative). Relative sensitivity 100% (95% CI: 93.5%-100%); relative specificity 99.3% (95% CI: 97.8%-100%). Prevalence study conducted on 451 lupus cohort sera; 9.98% positive rate, consistent with literature (12-20%). Precision testing (n=24) showed CVs <15% for most samples. Linearity confirmed via serial dilution (r > 0.99). No cross-reactivity observed with Ro, La, Scl-70, Jo-1, Sm, RNP, or DNA antibodies.

Technological Characteristics

Enzyme-linked immunosorbent assay (ELISA) using purified Ribosomal P antigen immobilized on solid-phase microtiter wells. Detection via enzyme-labeled anti-human IgG conjugate and substrate-induced colorimetric reaction. Photometric measurement of color intensity. Semi-quantitative assay.

Indications for Use

Indicated for the detection and semi-quantitation of IgG antibodies to Ribosomal P in human serum specimens as an 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).

Submission Summary (Full Text)

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K950169

MAY 23 1996

Summary of Safety and Effectiveness Information Ribosomal P ELISA Test Kit

I. Immuno Probe Inc.
1306 Bailes Lane, Suite F
Frederick, Maryland
Contact person: William Boteler
Telephone: [phone]
Date of preparation: December 22, 1995

II. Description of Device

The Ribosomal P ELISA test is an enzyme-linked immunosorbent assay (ELISA) for the detection and semi-quantitation of IgG antibodies to Ribosomal P in human sera. The assay is to be used to detect 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). FOR IN VITRO DIAGNOSTIC USE.

The Ribosomal P ELISA test is an enzyme linked immunosorbent assay to detect IgG, M, A, antibodies to Ribosomal P. Purified Ribosomal P antigen is 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 IgG, M, A 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.

III. Clinical Data

Clinical studies were conducted using 451 sera from a lupus cohort. Forty five were found to be positive for a prevalence rate of 9.98%. The data indicate that the prevalence of Ribosomal P antibody found in this cohort using the Ribosomal P device is similar to that found in the literature (12-20%).

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# XI. Performance Characteristics

1. Relative sensitivity and specificity. The Ribosomal P ELISA test results were compared to results obtained by ouchterlony analysis of serum from clinically defined lupus (n=46) and normals (n=137). The results of the study are summarized in Table 1.

Table 1 Sensitivity and Specificity of the Ribosomal P Test Kit Relative toOuchterlony

| | | Immuno Probe, Inc. | | | |
| --- | --- | --- | --- | --- | --- |
| | | Positive | Equivocal | Negative | Total |
| Ouchterlony | Positive | 46 | 0 | 0 | 46 |
| | Negative | 1 | 0 | 136 | 137 |
| | Total | 47 | 0 | 136 | 183 |
| Relative Sensitivity = 46/46 = 100% | | | 95% Confidence Interval = 93.5%-100% | | |
| Relative Specificity = 136/137 = 99.3% | | | 95% Confidence Interval = 97.8%-100% | | |
| Relative Agreement = 182/183 = 99.5% | | | 95% Confidence Interval = 98.4%-100% | | |

The 95% confidence interval for relative sensitivity was calculated assuming one false negative.

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## 2. Precision

The precision of the Ribosomal P kit was determined by testing seven different sera eight times each on three different assays. The data is summarized in Table 2. With proper technique the user should obtain C.V.'s of less than 15%.

Table 2 Ribosomal P Precision Data

| | Assay 1 (n=8) | | | Assay 2 (n=8) | | | Assay 3 (n=8) | | | Inter Assay (n=24) | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Serum # | X | S.D. | C.V. | X | S.D. | C.V. | X | S.D. | C.V. | X | S.D. | C.V. |
| 1 | 1.57 | 0.117 | 7.4% | 1.62 | 0.113 | 7.0% | 1.50 | 0.134 | 8.9% | 1.57 | 0.127 | 8.1% |
| 2 | 1.68 | 0.176 | 10.5% | 1.60 | 0.095 | 5.9% | 1.66 | 0.148 | 8.9% | 1.65 | 0.143 | 8.7% |
| 3 | 2.98 | 0.113 | 3.8% | 2.83 | 0.128 | 4.5% | 2.74 | 0.127 | 4.6% | 2.85 | 0.155 | 5.5% |
| 4 | 2.89 | 0.115 | 4.09% | 2.95 | 0.135 | 4.6% | 2.94 | 0.068 | 2.3% | 2.92 | 0.109 | 3.7% |
| 5 | 0.29 | 0.027 | 9.29% | 0.18 | 0.035 | 19.6% | 0.20 | 0.039 | 19.6% | 0.22 | 0.056 | 25.6% |
| 6 | 0.09 | 0.042 | 46.3% | 0.08 | 0.016 | 20.5% | 0.08 | 0.037 | 46.5% | 0.10 | 0.048 | 48.0% |

X = Mean Ribosomal P Value
S.D. = Standard Deviation
C.V. = Coefficient of Variation

## 3. Linearity

The Ribosomal P index values were determined for serial twofold dilutions of five positive sera. The index values were compared to $\log_2$ of dilution by standard linear regression. The data in table # 3 indicates that the assay is semi-quantitative.

Table 3 Linearity

| Index
Serum # | Neat | 1:2 | 1:4 | 1:8 | 1:16 | 1:32 | 1:64 | 1:128 | r |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 2.70 | 2.52 | 2.24 | 1.93 | 1.57 | 1.33 | 0.98 | | 0.997 |
| 2 | 2.53 | 2.29 | 1.99 | 1.57 | 1.20 | 0.86 | | | 0.997 |
| 3 | 2.89 | 2.71 | 2.47 | 2.23 | 1.93 | 1.57 | 1.20 | 0.90 | 0.994 |
| 4 | 3.68 | 3.18 | 2.59 | 1.94 | 1.59 | 1.00 | 0.68 | | 0.997 |
| 5 | 2.09 | 1.38 | 0.94 | | | | | | 0.991 |

Linear regression compared Ribosomal P Index Value to $\log_2$ of dilution

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# 4. Cross Reactivity Data

Sera containing high levels of antibodies to potentially cross reactive antigens were assayed on the Ribosomal P ELISA kit. The data in Table 4 indicates that antibodies to alternate autoimmune antigens do not cross react with the Ribosomal P ELISA kit.

Table 4 Cross Reactivity

| Serum # | Immunoprobe Index Value | Interpretation | Specificity |
| --- | --- | --- | --- |
| 1 | 0.21 | - | Ro |
| 2 | 0.18 | - | Ro |
| 3 | 0.17 | - | Ro |
| 4 | 0.13 | - | La |
| 5 | 0.09 | - | La |
| 6 | 0.10 | - | La |
| 7 | 0.09 | - | Scl-70 |
| 8 | 0.18 | - | Scl-70 |
| 9 | 0.17 | - | Scl-70 |
| 10 | 0.15 | - | Jo-1 |
| 11 | 0.18 | - | Jo-1 |
| 12 | 0.15 | - | Jo-1 |
| 13 | 0.38 | - | Sm |
| 14 | 0.43 | - | Sm |
| 15 | 0.40 | - | Sm |
| 16 | 0.19 | - | RNP |
| 17 | 0.15 | - | RNP |
| 18 | 0.14 | - | RNP |
| 19 | 0.14 | - | DNA |

5. Prevalence. Clinical studies were conducted using 451 sera from a lupus cohort. Forty five were found to be positive for a prevalence rate of 9.98%. The data indicate that the prevalence of Ribosomal P antibody found in this cohort using the Ribosomal P device is similar to that found in the literature (12-20%).