Name: Human Serum Anti-aquaporin-4 Immunoglobulin G Detection by Cell-based Assay (Video) | JoVE Journal
Uploaded: 2019-04-05T12:30:00.000+00:00
Duration: 5 min 45 s
Description: Learn cell-based assay techniques for detecting anti-AQP4 IgG in human serum samples. This sensitive method facilitates accurate diagnosis of neuromyelitis optica spectrum disorders in clinical settings.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

The authors are grateful for the support from grants from the National Science Foundation of China (No. 31600820), The Health and Family Planning Commission of Jilin Province (No. 2016Q036), and The Science and Technology Planning Project of Jilin Province (No. 20180520110JH).

This procedure was approved by the Ethics Committee of the First Hospital of Jilin University and was performed on approximately 1,500 subjects.
1. Patient Enrollment and Blood Sample Collection
<ol>
	<li>Apply the laboratory detection of serum anti-AQP4 IgG to clinic patients with the chief complaints and symptoms listed below. Perform physical examinations as well. 
	 
	Optic neuritis: Patients suffer with visual deficits, such as loss of visual fields and reduction of visual acuity. 
	Acute myelitis: Patients may present with paralysis, sensory deficits and autonomic dysfunction. 
	Area postrema syndrome: Patients may have symptoms of unexplained hiccups, nausea or vomiting. 
	Acute brainstem syndrome: Brainstem lesions could result in different symptoms and physical signs depending on the location of the lesions. 
	Symptomatic narcolepsy or acute diencephalic clinical syndrome with NMOSD-typical diencephalic MRI lesions. 
	Symptomatic cerebral syndrome with NMOSD-typical brain lesions. 
	 
	NOTE: According to the international consensus diagnostic criteria for NMOSD5, a diagnosis of NMOSD can be made if the patient is serum anti-AQP4 IgG-positive and has at least one of the core clinical characteristics mentioned above. However, we do not recommend testing of anti-AQP4 IgG in patients with optic neuritis only.</li>
	<li>Blood sample collection 
	&#8203;NOTE: Patients do not need to be fasting.
	<ol>
		<li>Draw 2-3 mL of venous blood in a 4 mL vacuum blood collection tube.</li>
		<li>Allow the serum to clot for 30 min at room temperature (RT). 
		NOTE: Prolonged clotting can increase serum levels due to leakage from platelets.</li>
		<li>Centrifuge at 2100 x g for 5 min. Carefully transfer the serum to a new tube.</li>
		<li>Analyze the serum immediately or aliquot and store at -20 or -80 &#176;C. 
		NOTE: Storage at -20 &#176;C is for storage of months, while -80 &#176;C is for storage of years.</li>
	</ol>
	</li>
</ol>
2. Anti-AQP4 Antibody Detection
CAUTION: Patient samples and used kit reagents should be considered infectious materials. Sodium azide-containing reagents in the kit are toxic. A flow chart of the protocol is provided in Figure 1.
<ol>
	<li>Preparation
	<ol>
		<li>Bring the kit to RT before use. 
		NOTE: Store the kit at 2-8 &#176;C.</li>
		<li>Prepare at least 200 mL of PBS wash buffer containing 0.2% Tween 20. Pour 100 mL of wash buffer into a 500 mL beaker.</li>
		<li>Dilute the serum samples 10x with wash buffer. Prepare the positive and negative controls according to the instructions of the distributor.</li>
	</ol>
	</li>
	<li>Sample incubation
	<ol>
		<li>Add 30 &#181;L of the pre-diluted samples, positive control, or negative control to the reaction fields of the reagent tray (Figure 2). 
		NOTE: Avoid air bubbles.</li>
		<li>Remove the protective cover on the biochip slides. 
		NOTE: Do not touch the biochips to avoid the detachment and contamination of fixed cells. Hold the slide side-by-side before removing the cover.</li>
		<li>Apply the biochip slide to the reagent tray (Figure 2). Start a 30 min incubation at RT. 
		NOTE: Every sample should be an individual droplet connected to the corresponding biochip without mixing with other droplets.</li>
		<li>Gently rinse the biochip slide once with wash buffer. Immerse the biochip slide into the 500 mL beaker filled with 100 mL of wash buffer for at least 5 min. Place the beaker on a shaker if possible.</li>
		<li>Take out the biochip slide from the wash buffer. Carefully wipe away the residual wash buffer outside of the reaction fields with a paper towel. Expose the biochip slide in open air for 1-2 min to evaporate the residual wash buffer on the reaction field. 
		NOTE: Do not dry out the reaction fields. Do not touch the biochips with paper towel.</li>
	</ol>
	</li>
	<li>Secondary antibody incubation
	<ol>
		<li>Prepare the secondary antibody solution according to the instructions of the distributor.</li>
		<li>Add 25 &#181;L of fluorescent secondary antibody to the reaction fields of a clean reagent tray.</li>
		<li>Apply the biochip slide to the reagent tray loaded with secondary antibody. Incubate for 30 min at RT.</li>
	</ol>
	</li>
	<li>Mounting
	<ol>
		<li>Pour out the used wash buffer and add 100 mL of fresh wash buffer into the beaker. Repeat the washing as described in steps 2.2.4 and 2.2.5.</li>
		<li>Carefully add embedding medium to the reaction fields on a biochip slide (one drop per reaction field). Seal the biochip slide with one piece of cover glass. Avoid air bubbles.</li>
	</ol>
	</li>
	<li>Fluorescence detection
	<ol>
		<li>Turn on the fluorescent lamp of microscope and pre-heat for 15 min. Choose a 488 nm filter.</li>
		<li>Open photograph software. Take pictures from both transfected and untransfected areas of all reaction fields with different magnifications. First, take one picture with 4x magnification for an overview, then take more pictures with 10x and 20x magnifications. 
		NOTE: The detailed protocol is shown in Table 1. Interpretation of the results is discussed in the representative results section.</li>
	</ol>
	</li>
</ol>
3. Diagnosis of Patients
<ol>
	<li>If the patient is serum anti-AQP4 IgG-positive and shows at least one core clinical characteristic of NMOSD (see discussion section), diagnose the patient with NMSOD5. However, if the patient is anti-AQP4 IgG-negative, a diagnosis of NMOSD may not be excluded.</li>
</ol>

<ol><li>Zekeridou, A., Lennon, V. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aquaporin-4+autoimmunity%5BTitle%5D)+AND+%22Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">Aquaporin-4 autoimmunity.</a> Neurology Neuroimmunology & Neuroinflammation. 2 (4), 110(2015).</li>
<li>Ho, J. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Crystal+structure+of+human+aquaporin+4+at+1.8+A+and+its+mechanism+of+conductance%5BTitle%5D)+AND+%22Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America%22%5BJournal%5D)">Crystal structure of human aquaporin 4 at 1.8 A and its mechanism of conductance.</a> Proceedings of the National Academy of Sciences of the United States of America. 106 (18), 7437-7442 (2009).</li>
<li>Takeshita, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+neuromyelitis+optica-IgG+at+the+blood-brain+barrier+in+vitro%5BTitle%5D)+AND+%22in+vitro.Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">Effects of neuromyelitis optica-IgG at the blood-brain barrier in vitro.</a> in vitro.Neurology Neuroimmunology & Neuroinflammation. 4 (1), 311(2016).</li>
<li>Sato, D. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Distinction+between+MOG+antibody-positive+and+AQP4+antibody-positive+NMO+spectrum+disorders%5BTitle%5D)+AND+%22Neurology%22%5BJournal%5D)">Distinction between MOG antibody-positive and AQP4 antibody-positive NMO spectrum disorders.</a> Neurology. 82 (6), 474-481 (2014).</li>
<li>Wingerchuk, D. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((International+consensus+diagnostic+criteria+for+neuromyelitis+optica+spectrum+disorders%5BTitle%5D)+AND+%22Neurology%22%5BJournal%5D)">International consensus diagnostic criteria for neuromyelitis optica spectrum disorders.</a> Neurology. 85 (2), 177-189 (2015).</li>
<li>Ruiz-Gaviria, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Specificity+and+sensitivity+of+aquaporin+4+antibody+detection+tests+in+patients+with+neuromyelitis+optica%3A+A+meta-analysis%5BTitle%5D)+AND+%22Multiple+Sclerosis+and+Related+Disorders%22%5BJournal%5D)">Specificity and sensitivity of aquaporin 4 antibody detection tests in patients with neuromyelitis optica: A meta-analysis.</a> Multiple Sclerosis and Related Disorders. 4 (4), 345-349 (2015).</li>
<li>Waters, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Multicentre+comparison+of+a+diagnostic+assay%3A+aquaporin-4+antibodies+in+neuromyelitis+optica%5BTitle%5D)+AND+%22Journal+of+Neurology%2C+Neurosurgery%2C+and+Psychiatry%22%5BJournal%5D)">Multicentre comparison of a diagnostic assay: aquaporin-4 antibodies in neuromyelitis optica.</a> Journal of Neurology, Neurosurgery, and Psychiatry. 87 (9), 1005-1015 (2016).</li>
<li>Fryer, J. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((AQP4+autoantibody+assay+performance+in+clinical+laboratory+service%5BTitle%5D)+AND+%22Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">AQP4 autoantibody assay performance in clinical laboratory service.</a> Neurology Neuroimmunology & Neuroinflammation. 1 (1), 11(2014).</li>
<li>Long, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aquaporin-4+antibody+in+neuromyelitis+optica%3A+re-testing+study+in+a+large+population+from+China%5BTitle%5D)+AND+%22The+International+Journal+of+Neuroscience%22%5BJournal%5D)">Aquaporin-4 antibody in neuromyelitis optica: re-testing study in a large population from China.</a> The International Journal of Neuroscience. 127 (9), 790-799 (2017).</li>
<li>Pisani, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aquaporin-4+autoantibodies+in+Neuromyelitis+Optica%3A+AQP4+isoform-dependent+sensitivity+and+specificity%5BTitle%5D)+AND+%22PloS+One%22%5BJournal%5D)">Aquaporin-4 autoantibodies in Neuromyelitis Optica: AQP4 isoform-dependent sensitivity and specificity.</a> PloS One. 8 (11), 79185(2013).</li>
<li>Jarius, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aquaporin-4+antibody+testing%3A+direct+comparison+of+M1-AQP4-DNA-transfected+cells+with+leaky+scanning+versus+M23-AQP4-DNA-transfected+cells+as+antigenic+substrate%5BTitle%5D)+AND+%22Journal+of+Neuroinflammation%22%5BJournal%5D)">Aquaporin-4 antibody testing: direct comparison of M1-AQP4-DNA-transfected cells with leaky scanning versus M23-AQP4-DNA-transfected cells as antigenic substrate.</a> Journal of Neuroinflammation. 11, 129(2014).</li>
<li>Juryńczyk, M., Craner, M., Palace, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Overlapping+CNS+inflammatory+diseases%3A+differentiating+features+of+NMO+and+MS%5BTitle%5D)+AND+%22Journal+of+Neurology%2C+Neurosurgery%2C+and+Psychiatry%22%5BJournal%5D)">Overlapping CNS inflammatory diseases: differentiating features of NMO and MS.</a> Journal of Neurology, Neurosurgery, and Psychiatry. 86 (1), 20-25 (2015).</li>
<li>Chen, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clinical+Features+of+Patients+with+Multiple+Sclerosis+and+Neuromyelitis+Optica+Spectrum+Disorders%5BTitle%5D)+AND+%22Chinese+Medical+Journal%22%5BJournal%5D)">Clinical Features of Patients with Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders.</a> Chinese Medical Journal. 129 (17), 2079-2084 (2016).</li>
<li>Majed, M., Fryer, J. P., McKeon, A., Lennon, V. A., Pittock, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clinical+utility+of+testing+AQP4-IgG+in+CSF%3A+Guidance+for+physicians%5BTitle%5D)+AND+%22Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">Clinical utility of testing AQP4-IgG in CSF: Guidance for physicians.</a> Neurology Neuroimmunology & Neuroinflammation. 3 (3), 231(2016).</li>
<li>Jarius, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cerebrospinal+fluid+antibodies+to+aquaporin-4+in+neuromyelitis+optica+and+related+disorders%3A+frequency%2C+origin%2C+and+diagnostic+relevance%5BTitle%5D)+AND+%22Journal+of+Neuroinflammation%22%5BJournal%5D)">Cerebrospinal fluid antibodies to aquaporin-4 in neuromyelitis optica and related disorders: frequency, origin, and diagnostic relevance.</a> Journal of Neuroinflammation. 7, 52(2010).</li>
<li>Asgari, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Disruption+of+the+leptomeningeal+blood+barrier+in+neuromyelitis+optica+spectrum+disorder%5BTitle%5D)+AND+%22Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">Disruption of the leptomeningeal blood barrier in neuromyelitis optica spectrum disorder.</a> Neurology Neuroimmunology & Neuroinflammation. 4 (4), 343(2017).</li>
<li>Kim, H. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((MRI+characteristics+of+neuromyelitis+optica+spectrum+disorder%3A+an+international+update%5BTitle%5D)+AND+%22Neurology%22%5BJournal%5D)">MRI characteristics of neuromyelitis optica spectrum disorder: an international update.</a> Neurology. 84 (11), 1165-1173 (2015).</li>
<li>Jarius, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((MOG+encephalomyelitis%3A+international+recommendations+on+diagnosis+and+antibody+testing%5BTitle%5D)+AND+%22Journal+of+Neuroinflammation%22%5BJournal%5D)">MOG encephalomyelitis: international recommendations on diagnosis and antibody testing.</a> Journal of Neuroinflammation. 15 (1), 134(2018).</li>
<li>Narayan, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((MOG+antibody+disease%3A+A+review+of+MOG+antibody+seropositive+neuromyelitis+optica+spectrum+disorder%5BTitle%5D)+AND+%22Multiple+Sclerosis+and+Related+Disorders%22%5BJournal%5D)">MOG antibody disease: A review of MOG antibody seropositive neuromyelitis optica spectrum disorder.</a> Multiple Sclerosis and Related Disorders. 25, 66-72 (2018).</li>
<li>Ogawa, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((MOG+antibody-positive%2C+benign%2C+unilateral%2C+cerebral+cortical+encephalitis+with+epilepsy%5BTitle%5D)+AND+%22Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">MOG antibody-positive, benign, unilateral, cerebral cortical encephalitis with epilepsy.</a> Neurology Neuroimmunology & Neuroinflammation. 4 (2), 322(2017).</li>
<li>Valentino, P., Marnetto, F., Granieri, L., Capobianco, M., Bertolotto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aquaporin-4+antibody+titration+in+NMO+patients+treated+with+rituximab%3A+A+retrospective+study%5BTitle%5D)+AND+%22Neurology+Neuroimmunology+%26+Neuroinflammation%22%5BJournal%5D)">Aquaporin-4 antibody titration in NMO patients treated with rituximab: A retrospective study.</a> Neurology Neuroimmunology & Neuroinflammation. 4 (2), 317(2016).</li>
<li>Kessler, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Anti-aquaporin-4+titer+is+not+predictive+of+disease+course+in+neuromyelitis+optica+spectrum+disorder%3A+A+multicenter+cohort+study%5BTitle%5D)+AND+%22Multiple+Sclerosis+and+Related+Disorders%22%5BJournal%5D)">Anti-aquaporin-4 titer is not predictive of disease course in neuromyelitis optica spectrum disorder: A multicenter cohort study.</a> Multiple Sclerosis and Related Disorders. 17, 198-201 (2017).</li>
<li>Mealy, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aquaporin-4+serostatus+does+not+predict+response+to+immunotherapy+in+neuromyelitis+optica+spectrum+disorders%5BTitle%5D)+AND+%22Multiple+Sclerosis%22%5BJournal%5D)">Aquaporin-4 serostatus does not predict response to immunotherapy in neuromyelitis optica spectrum disorders.</a> Multiple Sclerosis. , (2017).</li>
<li>Yang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+role+of+aquaporin-4+antibodies+in+Chinese+patients+with+neuromyelitis+optica%5BTitle%5D)+AND+%22Journal+of+Clinical+Neuroscience%22%5BJournal%5D)">The role of aquaporin-4 antibodies in Chinese patients with neuromyelitis optica.</a> Journal of Clinical Neuroscience. 20 (1), 94-98 (2013).</li>
<li>Kitley, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prognostic+factors+and+disease+course+in+aquaporin-4+antibody-positive+patients+with+neuromyelitis+optica+spectrum+disorder+from+the+United+Kingdom+and+Japan%5BTitle%5D)+AND+%22Brain%22%5BJournal%5D)">Prognostic factors and disease course in aquaporin-4 antibody-positive patients with neuromyelitis optica spectrum disorder from the United Kingdom and Japan.</a> Brain. 135 (6), 1834-1849 (2012).</li>
</ol>

The authors have nothing to disclose.

We have described a widely accessible method to detect anti-AQP4 IgG in human serum. Anti-AQP4 IgG is closely related to NMOSD, and establishing a reliable anti-AQP4 IgG detection method is crucial for the clinical diagnosis of NMOSD. First, anti-AQP4 IgG is specific for NMOSD. Multiple sclerosis is also an immune-mediated disease of the central nervous system and shares many similarities with NMOSD12. However, anti-AQP4 IgG is only positive in NMOSD13. Second, anti-AQP4 Ig...

Serum AQP4 IgG is a core diagnostic biomarker for neuromyelitis optica spectrum disorders (NMOSD)1. The cell-based assay (CBA) is a widely used anti-AQP4 IgG detection method with high sensitivity and specificity. Here, a detailed protocol for CBA is introduced.
AQP4, a water channel protein, has six membrane-spanning units and two helical domains surrounding one aqueous pore2. Anti-AQP4 IgG is involved in the pathogenesis of NMOSD through binding to its target AQP4, which is mainly located on the endfeet of astrocytes3. It has been shown that anti-AQP4 IgG is positive in approximately two-thirds of NMOSD patients4. In the most recent international diagnostic criteria for NMOSD, anti-AQP4 IgG is considered to be a core diagnostic biomarker5. In this regard, it is crucial to establish a reliable protocol to detect human serum anti-AQP4 IgG and facilitate clinical diagnosis of NMOSD.
Currently, various anti-AQP4 IgG detection methods are available, such as CBA, tissue-based assay, enzyme-linked immunosorbent assay, and flow cytometry6,7. CBA employs EU90 cells, which are transfected with human AQP4, to capture anti-AQP4 IgG. The captured anti-AQP4 IgG is detected by fluorescent secondary antibodies and subsequently visualized by microscopy. Accumulating evidence has shown that CBA is more sensitive and specific than other anti-AQP4 IgG detection methods6,7. According to a meta-analysis, the sensitivity and specificity of CBA were shown to be 76% and 99%, which were higher than tissue-based and enzyme-linked immunosorbent assays6. Furthermore, a multicenter comparison of diagnostic assays of anti-AQP4 IgG was conducted7. A total of 193 study subjects from 15 European diagnostic centers were enrolled7. Four different methods were utilized to detect serum anti-AQP4 IgG7. It was demonstrated that CBA was more sensitive and specific than the other methods7. As AQP4 is expressed as two major isoforms (AQP4-M1 and AQP4-M23), anti-AQP4 IgG capture cell is transfected with either AQP4-M1 or AQP4-M23. However, which type of capture cell is better remains controversial. One investigation has supported AQP4-M1 based CBA8, while others have indicated that AQP4-M23 based CBA is better7,9,10. However, AQP4-M23-based CBA may yield false positive results due to unspecific IgG binding8. Jarius et al.11 reported that there was no significant difference in anti-AQP4 IgG detection rates between AQP4-M1 and AQP4-M23-based CBAs.
In summary, serum anti-AQP4 IgG is a core biomarker for NMOSD. CBA has higher specificity and sensitivity than other anti-AQP4 IgG detection methods. It remains controversial whether AQP4-M1- or AQP4-M23-based CBA is better. In this article, a detailed protocol for AQP4-M1-based CBA is described, which can apply to clinical diagnosis and studies of NMOSD.

<table><tbody><tr><td>Anti-aquaporin-4 IIFT</td><td>Euroimmun</td><td>FA 1128-2005-50</td><td>Contains biochip slides coated with AQP4-M1 transfected and untransfected EU 90 cells, fluorescein-labelled anti-human IgG, anti-AQP4 antibody as positive control, antibody negative sample, salt for PBS pH 7.2, Tween 20 and embedding medium.&amp;nbsp;</td></tr><tr><td>CellSens Dimension</td><td>OLYMPUS</td><td>N/A</td><td>photograph software</td></tr><tr><td>Gel &amp;amp; clot activator tube</td><td>Improve medical</td><td>623040202</td><td>From a local Chinese company</td></tr></tbody></table>

human serum anti-aquaporin-4 immunoglobulin g detection by cell-based assay

Human Serum Anti-aquaporin-4 Immunoglobulin G Detection by Cell-based Assay

Anti-aquaporin-4 (AQP4) immunoglobulin G (IgG) is the core diagnostic biomarker for neuromyelitis optica spectrum disorders (NMOSD). The cell-based assay (CBA) is a widely used method to detect anti-AQP4 IgG in human serum with high sensitivity and specificity. Briefly, serum anti-AQP4 IgG is captured by AQP4-transfected cell that is fixed on the biochip then detected by a fluorescein-labelled secondary antibody. Fluorescence microscopy is utilized to visualize the fluorescence, and the intensity of fluorescence is evaluated by at least two experienced clinicians. A final diagnosis of NMOSD can be made based on the combination of anti-AQP4 IgG detection results, clinical manifestations, and neuroradiological findings. According to previous studies, CBA is more sensitive and specific than other anti-AQP4 IgG detection methods, and it can be applied to both clinical diagnosis and studies of NMOSD. The method has limitations; for example, an international scale to evaluate serum anti-AQP4 IgG titers is still lacking. Here, a detailed protocol for human serum anti-AQP4 IgG detection using CBA is described.

Using the procedure described here, specific anti-AQP4 IgG in serum is detectable. During the procedure, pre-diluted samples, a positive control, and a negative control were added to the reaction fields, which contain transfected and untransfected areas (Figure 2). Fluorescence of the negative control in a transfected area mainly indicated the unspecific binding of secondary antibody to the transfected cells on biochips (Figure 3...

Cell-based assay is a widely used method to detect serum anti-aquaporin-4 immunoglobulin G. This method could be applied to clinical diagnosis and scientific researches of neuromyelitis optical spectrum disorders.

Anti-aquaporin-4 (AQP4) immunoglobulin G (IgG) is the core diagnostic biomarker for neuromyelitis optica spectrum disorders (NMOSD). The cell-based assay ...

human-serum-anti-aquaporin-4-immunoglobulin-g-detection-cell-based

Research

JoVE Journal

Immunology and Infection

This video demonstrates the hydrophobic interaction liquid chromatography-based characterization of antibody-drug conjugates. Using a butyl ligand-based chromatography column, the antibody-drug conjugates are characterized via hydrophobic interactions with the ligand.

Butyl-Dependant Hydrophobic Interaction Liquid Chromatography: A Technique to Characterize Antibody-Drug Conjugates Based on Hydrophobic Interactions

This video describes an immunoassay technique using fluorescent magnetic beads or microspheres coupled with different antigens to simultaneously detect various antibody isotypes in a serum sample. The assay is helpful in understanding seroconversion during an infection or post-vaccination.

Multianalyte Immunobead Assay: A Flow-Based Immunoassay Technique for Concurrent Detection of Multiple Antibody Subtypes in Human Serum Sample

The video demonstrates a cell-based assay for detecting anti-aquaporin-4 immunoglobulin G using a biochip containing untransfected cells and transfected cells expressing aquaporin-4. This method has applications in diagnosing neuromyelitis optica spectrum disorders, confirmed by strong green fluorescence on the biochip.

An Assay to Detect Serum Anti-aquaporin-4 Immunoglobulin G

The video demonstrates a paper-based immunoassay, involving amine-functionalized cellulose discs cross-linked with glutaraldehyde. Covalent immobilization of IgG-Fc-specific capture antibodies, followed by the introduction of immunoglobulin G and horseradish peroxidase-conjugated detection antibodies, results in a color change confirming the presence of immunoglobulin G.

A Paper-Based Immunoassay for the Detection of Immunoglobulin G

Over the recent years, live cell-based assays have been used successfully to detect antibodies against surface and conformational antigens. Here, we describe a method using high-throughput flow cytometry enabling the analysis of large cohorts of patients. Detection of novel antibodies will improve diagnosis and treatment of immune-mediated disorders.

High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum

Here we describe two assays for measuring complement activation induced by antibodies against red blood cells. The major advantage over the current assays is their quantitative and easy-to-interpret nature.

Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells

This article describes a simple protein microarray method for profiling humoral immune responses to a 7-plex panel of highly purified Clostridium difficile antigens in human sera. The protocol can be extended for the determination of specific antibody responses in preparations of polyclonal intravenous immunoglobulin.

A Protein Microarray Assay for Serological Determination of Antigen-specific Antibody Responses Following Clostridium difficile Infection

Here we present a cell-based flow cytometry method to detect neutralizing antibodies or other factors that interfere with the cellular uptake of enzyme replacement therapies in a human matrix, such as cerebral spinal fluid (CSF) or human serum.

Detection of Antibodies That Neutralize the Cellular Uptake of Enzyme Replacement Therapies with a Cell-based Assay

The BSelex method to identify and recover individual antigen-specific antibodies from human peripheral blood mononuclear cells combines flow cytometry with single cell PCR and cloning.

Single-cell Screening Method for the Selection and Recovery of Antibodies with Desired Specificities from Enriched Human Memory B Cell Populations

We present a protocol for using a protein microarray constructed by printing influenza antigens onto nitrocellulose-coated slides to simultaneously probe serum for multiple antibody isotypes against over 250 antigens from different virus strains, thus allowing measurement of the breadth of serum antibodies across virus subtypes.

Use of an Influenza Antigen Microarray to Measure the Breadth of Serum Antibodies Across Virus Subtypes

Learn cell-based assay techniques for detecting anti-AQP4 IgG in human serum samples. This sensitive method facilitates accurate diagnosis of neuromyelitis optica spectrum disorders in clinical settings.

Human Serum Anti-aquaporin-4 Immunoglobulin G Detection by Cell-based Assay

Explore More Videos