SS-B(La) Antibody IgG ELISA Kit

Name: SS-B(La) Antibody IgG ELISA Kit
SKU: DEIA1688
Rating: 5 (1 reviews)

Regulatory status: For research use only, not for use in diagnostic procedures.

COA

SDS

Datasheet

Summary

Sample

Serum and Plasma

Species Reactivity

Human

Detection Method

iELISA

Intended Use

Enzyme immunoassay for the qualitative and quantitative determination of IgG antibodies against SS-B/La in human serum or plasma (EDTA, citrate, heparin).

Contents of Kit

1. MTP Microtiter Plate, coated with the SS-B / La antigen described above and hermetically packed in a foil laminate pouch together with a desiccant bag. The plate consists of 12 strips, each of which can be broken into 8 individual wells.
2. ENZCONJ IgG Enzyme Conjugate, 14 mL, ready-to-use, red coloured. Buffered solution containing stabilising protein, methylisothiazolone and bromonitrodioxane.
3. CAL A–F Calibrator A-F, 2,0 mL each, 0 - 0,60 - 2,0 - 6,0 - 20 and 60 U SS-B / La IgG / mL, ready-to-use, gradually blue coloured. Contain TBS, BSA, Tween and Na-azide.
4. CONTROL - & CONTROL + Negative and Positive Control, 2,0 mL each, ready-to-use, green and red coloured, respectively. Contain TBS, BSA, Tween and Na-azide.
5. SAMPLEDIL Sample Diluent, 100 mL, ready-to-use, orange coloured. Contains Tris-buffered saline (TBS), bovine serum albumin (BSA), Tween and Na-azide.
6. TMB SUBS TMB Substrate Solution, 14 mL, ready-to-use, colourless. Contains a buffered solution of TMB and H₂O₂. Contained in a vial impermeable to light.
7. WASHBUF CONC Wash Buffer, 100 mL, 10x-concentrate, blue coloured. Contains TBS, Tween and bromonitrodioxane.
8. STOP TMB Stop Solution (0,2 M H₂SO₄), 14 mL, colourless, ready-to-use.
Caution: sulfuric acid is corrosive.
9. Instructions for use
10. Lot-specific certificate of analysis

Storage

2-8°C

Performance Characteristics

Standardisation
The test is standardised with a purified serum preparation containing IgG antibodies specifically directed at the SS-B / La antigen. This preparation is calibrated against a set of gradually positive sera, solely reserved for this purpose. The degree of sample reactivity is measured in arbitrary units (U/mL) since no international standard is available.
Analytical specificity
The test allows the specific determination of human IgG antibodies directed against SS-B / La. It has been validated (among other parameters) by means of the commercially available human reference sera of the "Center of Disease Control" (CDC, Atlanta, USA). The following results are typical:

Interference with anticoagulants (EDTA, Citrat, Heparin) in samples has been tested and no interference effects have been observed.
Homogeneity of the solid phase
Measurement of the solid phase homogeneity is a regular QC part of each production lot. This is determined by 288-fold measurement of a positive but non-saturating sample on 3 selected plates. Acceptance criterion: mOD-coefficient of variation (cv) over the plates < 8%. The figure below shows a representative excerpt of such an analysis.

Frequency distribution of SS-B / La IgG
This was analysed in a sera collective of blood donors, equally distributed by sex and age, and a collective of sera intended-positive in different ring trials or clinically defined and/or found positive for SS-B / La IgG autoantibodies according to a FDA-approved, CE-compliant reference ELISA. The following distribution of the analyte was observed:

ROC-analysis of these data was used to determine the cut-off as 10,0 U SS-B / La IgG / mL (9). The data presented here suggest a diagnostic specificity and sensitivity of the ELISA of 100 % for both parameters. These values apply for the measured sera only; other collectives may yield different results. In view of the low number of positive sera, particular caution is required when interpreting test sensitivity.

Detection Limit

The detection limit is defined as that concentration of analyte that corresponds to the mean absorbance of Sample Diluent plus 3-fold standard deviation (s). It was determined as < 0,2 U SS-B / La IgG per mL sample (n = 24).
Recommended measuring range: 0,5 - 50 U / mL

General Description

The present ELISA is intended for the quantitative or qualitative determination of IgG antibodies in human serum or plasma, directed against the SS-B / La antigen. This is a recombinant, highly purified
preparation of the human protein, expressed by baculovirus infected insect cells. The test is fast (incubation time 30 / 30 / 30 minutes) and flexible (divisible solid phase, ready-to-use reagents). Six calibrators allow quantitative measurements; a negative and a positive control check the assay performance.
SS-B / La IgG ELISA is an enzyme-linked immunosorbent assay (ELISA) intended for the quantitative or qualitative determination of IgG class antibodies directed against SS-B / La in human serum or plasma samples. Its function is the aid to differential diagnosis of inflammatory autoimmune diseases, especially Sjoegren's syndrome and systemic lupus erythematosus.

Standard Curve

General Notes

Citations

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Background

SSB/La or Sjögren Syndrome Antigen B or Lupus La protein is a human gene-encoded RNA-binding protein that is ubiquitous. It is essential to several metabolic steps in RNA – such as RNA processing, stabilization and folding. SSB/La is a complex protein involved in critical cell functions in RNA metabolism, immune function and epigenetic regulation. The immune system misperceives it and misrecognises it, resulting in autoimmune disorders such as Sjögren's syndrome and lupus.

SSB/La binds to the 3' ends of newly synthesized RNA polymerase III transcripts, such as precursor tRNAs, protecting them from exonuclease degradation. This activity ensures proper RNA maturation and processing. La functions as an RNA chaperone, assisting in the correct folding of certain mRNAs and other RNAs. This is crucial to RNA stability and function in the cell. Moreover, La protein can also bind to viral RNAs (including the one from hepatitis C virus) so that they are stable and translated in the host cell. Recent work has implicated SSB/La in X chromosome deletion (XCI), by attaching to Xist RNA, a long non-coding RNA that silences one of the X chromosomes in female cells. Knockdown of SSB/La leads to defects in XCI, indicating its crucial role in this epigenetic process.

SSB/La is an autoantigen associated with autoimmune diseases like Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE). Autoantibodies against La are commonly found in patients with these conditions. Anti-SSB/La is one of the common and important serologic features in SS. Overactive B cells and chronic lag in plasma cells result in a diverse set of autoantibodies. Autoantibodies that tend to be present ahead of disease manifestations are antinuclear antibodies (ANA), RF, anti-Ro/SSA, and anti-La/SSB. The earlier the antibodies are identified, the more anti-Ro/SSA antibodies in asymptomatic pregnant women can result in passive acquired autoimmunity in the infant (neonatopathic lupus syndrome, congenital heart block) due to transplacental transmission of the antibodies.

Effects of anti-SSB/La on autoimmunity Figure 1. Schema depicting the effects of anti-SSB/La autoantibodies on neutrophil and macrophage functions, and autoimmunity
(Source: Yu C, et al. 2013)

Alternative Names

Sjögren Syndrome Antigen B Antibody
Lupus La protein Antibody

References

1. Veenbergen S, et al. Autoantibodies in Sjögren's syndrome and its classification criteria. J Transl Autoimmun. 2021 Dec 27;5:100138.
2. Yu C, et al. Autoantibody profiling in systemic lupus erythematosus. Current Biomarker Findings. 2013 Aug;3:55.

Documents

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References

Photonics-Assisted Frequency Up/Down Conversion With Tunable OEO and Phase Shift

JOURNAL OF LIGHTWAVE TECHNOLOGY

Authors: Yang, Feng; Wang, Dayong; Wang, Yunxin; Chen, Zhiyu; Zhou, Tao; Yang, Dengcai; Zhong, Xin; Zhang, Hongbiao

Abstract

A novel photonics-assisted method for frequency up/down-conversion based on an integrated dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) with tunable optoelectronic oscillator (OEO) and phase shift is presented. The local oscillator (LO) signal with high spectral purity and low phase noise is generated by an OEO loop in one of the sub-DPMZMs. The frequency can be adjusted by an electrical bandpass filter (EBPF). The radio frequency (RF) signal is injected into another sub-DPMZM. The carrier-suppressed singlesideband (CS-SSB) modulation of both the LO and RF signals is achieved. The phase of the converted signal can be tuned by an integrated dual-channel phase modulator (DPM). Frequency up/down-conversion can be switched by tuning a single bias voltage of the DP-DPMZM. Multiple functions, including tunable LO signal generation, up/down-conversion and phase shifting, can be realized. Moreover, dispersion-induced power fading is well compensated due to CS-SSB modulation. In the experiments, the tunable LO signal from 5 to 18 GHz, with a sidemode suppression ratio as high as 46.1 dB and a phase noise level of-104.5 dBc/Hz@ 10 kHz at 10 GHz, is generated successfully. The spur suppression ratios of the up/down-converted signals are 32.6 dB and 35.6 dB, respectively. The up/down conversion performance forRFcarrying 16 quadrature amplitude modulation (16-QAM) signal is also investigated. The phase shifting of dual-channel converted signals can be varied continuously and independently in the range of 0-360 degrees, and the phase deviation is +/- 1.8 degrees. The proposed compact link is characterized by function multiplexing and inherent dispersion compensation.

Prediction of outcome in fetal autoimmune complete heart block

PRENATAL DIAGNOSIS

Authors: Sethi, Neeta; Krishnan, Anita; Donofrio, Mary

Abstract

Assessing cardiac function and risk stratification in a fetal anti-Sjogren syndrome type A (SSA) or anti-Sjogren syndrome type B (SSB) complete atrioventricular block (CAVB) is challenging. We aimed to evaluate the cardiovascular profile score (CVP) and its components in surveillance of fetuses with autoimmune CAVB. Methods Retrospective cohort review of CAVB pregnancies, excluding fetuses with significant cardiac anomalies. Results CAVBs are in 17 fetuses, diagnosed at mean gestational age of 23 +/- 5 weeks. Overall mortality is 18%: 1 termination, 1 fetal demise (intrauterine fetal demise [IUFD]), and 1 postnatal death. Both mortalities had intrauterine growth restriction; IUFD had placental infarction. Presenting CVP 8.7 +/- 1. No fetus had CVP <7; the score correlated with increased risk of perinatal death. The 2 mortalities had initial CVP scores of 8 and 9; both increased to 10 on subsequent exams. 30% of fetuses had low middle cerebral artery pulsatility (MCA-PI) on the last study. All had high umbilical artery pulsatility (UA-PI) throughout gestation. The 2 deaths had the lowest MCA-PI. Conclusion Despite low heart rates, high CVP scores in our cohort remained high and were not predictive of mortality. Abnormalities in MCA flow reflects fetal cerebral vasodilation that may indicate altered hemodynamics and be predictive of outcomes, but data is limited. Abnormal umbilical artery (UA) flow suggests that perinatal mortality may also be related to placental disease.