Test Id : SLA
Soluble Liver Antigen (SLA) IgG Antibodies, Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluation of patients at-risk for autoimmune hepatitis or liver disease of unknown etiology
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For information see First-Line Screening for Autoimmune Liver Disease Algorithm.
Method Name
A short description of the method used to perform the test
Enzyme-Linked Immunosorbent Assay (ELISA)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
AIH
Autoimmune hepatitis
FSLAA
Liver Autoantibody
SLA
UGA suppressor tRNA
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For information see First-Line Screening for Autoimmune Liver Disease Algorithm.
Specimen Type
Describes the specimen type validated for testing
Serum
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL Serum
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
If not ordering electronically, complete, print, and send Gastroenterology and Hepatology Test Request (T728) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
Serum: 0.4 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
| Heat treated specimens | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 21 days | |
| Frozen | 21 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluation of patients at-risk for autoimmune hepatitis or liver disease of unknown etiology
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For information see First-Line Screening for Autoimmune Liver Disease Algorithm.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Autoimmune hepatitis (AIH) is a chronic liver disease characterized by the presence of diverse autoantibodies, increased concentrations of specific liver enzymes, hypergammaglobulinemia and abnormalities in liver histology.(1-3) AIH affects all ages and races and is categorized into type 1 (AIH-1) and type 2 (AIH-2). AIH-1 is by far more common and affects both children and adults, whereas AIH-2 is mainly a pediatric disease.(3,4) AIH-1 is characterized by positive anti-nuclear antibody (ANA) and/or anti-smooth muscle antibody (SMA), whereas AIH-2 is characterized by positive anti-liver kidney microsomal antibody type 1 (LMK-1) and/or anti-liver cytosol type 1 antibodies.(3,4) Anti-soluble liver antigen (anti-SLA) antibody, a disease-specific autoantibody, is seen in both AIH-1 and AIH-2, a feature that, coupled with its high disease specificity, suggests a key pathophysiological role of its antigenic target in the disease process.(3-5) Also referred to as anti-SLA/LP (liver-pancreas) antibody, it was originally identified by Manns M, et al in 1987(6) in patients HBsAg-negative chronic active hepatitis.(reviewed in 3) The SLA autoantibodies were subsequently identified as targeting O-phosphoseryl-tRNA:selenocysteine-tRNA synthase (SepSecS), a 56 kDa cytosolic protein of 501 amino acids detected in both AIH-1 and AIH-2 and are the only disease-specific AIH-associated autoantibody.(3,7)
Anti-soluble liver antigen (anti-SLA) antibody testing is recommended in American Association for the Study of Liver Diseases/International Autoimmune Hepatitis Group (AASLD/IAIHG) guidelines for AIH, especially for identifying patients with cryptogenic hepatitis with features of autoimmune disease.(1,2) Although they appear in only 20% to 30% of AIH or 10% to 30% in cryptogenic (unexplained) chronic hepatitis patients, they are crucial for diagnosis as they can be the sole marker in "seronegative" cases (negative for ANA/SMA).(3,5,8) Anti-SLA antibodies can also be detected in some patients with primary biliary cholangitis-AIH overlap syndrome.(3) In addition, some studies have noted that anti-SLA-positive patients might show lower serum aspartate aminotransferase (AST) levels and lower-globulins compared to ANA/SMA positive patients at diagnosis.(9) Anti-SLA antibodies are very specific for AIH, appearing rarely in healthy individuals and other non-hepatic autoimmune conditions.(3,8) In general, patients positive for anti-SLA antibodies appear to have clinical, histological, and laboratory features to non-SLA positive AIH-1 patients.(8) Although anti-SLA positivity has been reported to demonstrate a more aggressive clinical course, these results appear to be inconclusive.(3,5,9-11) Possibly due to the rarity of anti-SLA antibody-positive AIH patients, characteristics of disease cohorts, or type of assay used in these studies.(3,5,9-11) Therefore, it is likely the requirement of lifelong immunosuppression and/or higher relapse rates after treatment withdrawal would be based on patient-specific factors, test method, or clinician's judgment.
Detection of anti-SLA antibodies primarily relies on solid-phase immunoassays (SPAs) rather than traditional indirect immunofluorescence assay (IFA).(3-5,8-11) This is because the target antigen-a 50 kDa cytosolic protein identified as seryl-tRNA:selenocysteinyl-tRNA synthase-is soluble and lost during the preparation of standard tissue substrates used in immunofluorescence assays (IFA).(reviewed in 3) Of the SPAs, the enzyme-linked immunosorbent assay was the first method to be validated for use in an international study and is most widely used test.(8,9) The line immunoassay is also another commonly used method.(10) These typically use recombinant human SLA/LP antigen to provide a qualitative and/or semi-quantitative measure of IgG antibodies in patient serum.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Negative: <20.0 U
Equivocal: 20.0-24.9 U
Positive: > or = 25.0 U
Interpretation
Provides information to assist in interpretation of the test results
A positive anti-SLA (soluble liver antigen) antibody test is highly specific marker for autoimmune hepatitis (AIH), especially in cases where other antibodies are absent. It occurs in approximately 10% to 30% of patients with AIH.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A negative result does not rule out AIH. It is a rare autoantibody and many patients with AIH are negative for this specific antibody. It can sometimes be the only positive antibody detected in cases of autoimmune liver disease.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. European Association for the Study of the Liver. EASL Clinical Practice Guidelines: Autoimmune hepatitis. J Hepatol. 2015;63(4):971-1004
2. Mack CL, Adams D, Assis DN, et al. Diagnosis and management of autoimmune hepatitis in adults and children: 2019 Practice Guidance and Guidelines from the American Association for the Study of Liver Diseases. Hepatology. 2020;72(2):671-722
3. Terziroli Beretta-Piccoli B, Mieli-Vergani G, Vergani D. Autoimmune hepatitis: Serum autoantibodies in clinical practice. Clin Rev Allergy Immunol. 2022;63(2):124-137
4. Vitozzi S, Djilali-Saiah I, Lapierre P, Alvarez F. Anti-soluble liver antigen/liver-pancreas (SLA/LP) antibodies in pediatric patients with autoimmune hepatitis. Autoimmunity. 2002;35(8):485-492
5. Ballot E, Homberg JC, Johanet C. Antibodies to soluble liver antigen: an additional marker in type 1 auto-immune hepatitis. J Hepatol. 2000;33(2):208-215
6. Manns M, Gerken G, Kyriatsoulis A, et al. Characterisation of a new subgroup of autoimmune chronic active hepatitis by autoantibodies against a soluble liver antigen. Lancet. 1987;1:292-294. doi:10.1016/S0140-6736(87)92024-1
7. Gelpi C, Sontheimer EJ, Rodriguez-Sanchez JL. Autoantibodies against a serine tRNA-protein complex implicated in cotranslational selenocysteine insertion. Proc Natl Acad Sci U S A. 1992;89(20):9739-9743
8. Baeres M, Herkel J, Czaja AJ, et al. Establishment of standardised SLA/LP immunoassays: specificity for autoimmune hepatitis, worldwide occurrence, and clinical characteristics. Gut. 2002;51(2):259-264
9. Chen ZX, Shao JG, Shen Y, et al. Prognostic implications of antibodies to soluble liver antigen in autoimmune hepatitis: A PRISMA-compliant meta-analysis. Medicine (Baltimore). 2015;94(23):e953
10. Yuksekyayla O, Kina N, Ulaba A, et al. The frequency and clinical significance of antibodies to soluble liver antigen/liver pancreas in autoimmune hepatitis: a prospective single-center study. Eur J Gastroenterol Hepatol. 2024;36(5):652-656
11. Zachou K, Weiler-Normann C, Muratori L, Muratori P, Lohse AW, Dalekos GN. Permanent immunosuppression in SLA/LP-positive autoimmune hepatitis is required although overall response and survival are similar. Liver Int. 2020;40(2):368-376
Method Description
Describes how the test is performed and provides a method-specific reference
Partially purified, full-length recombinant human soluble liver antigen (SLA) is bound to the wells of a polystyrene microwell plate under conditions that will preserve the antigen in its native state. Prediluted controls and diluted patient sera are added to separate wells, allowing any SLA antibodies present to bind to the immobilized antigen. Unbound sample is washed away and an enzyme labeled anti-human IgG conjugate is added to each well. A second incubation allows the enzyme labeled anti-human IgG to bind to any patient antibodies that have become attached to the microwells. After washing away any unbound enzyme labeled anti-human IgG, the remaining enzyme activity is measured by adding a chromogenic substrate and measuring the intensity of the color that develops. The assay can be evaluated spectrophotometrically by measuring and comparing the color intensity that develops in the patient wells with the color in the control wells.(Package insert: QUANTA Lite SLA ELISA 708775. INOVA Diagnostics; Rev. 6, 11/2021)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
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- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
83516
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| SLA | Soluble Liver Antigen Ab, IgG, S | 32219-8 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| SLA | Soluble Liver Antigen Ab, IgG, S | 32219-8 |