Test Catalog

Test Id : HTLLC

Human T-Cell Lymphotropic Virus Types 1 and 2 (HTLV-1/-2) Antibody Confirmation, Spinal Fluid

Useful For
Suggests clinical disorders or settings where the test may be helpful

Confirmatory detection of human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2)-specific IgG antibodies in spinal fluid specimens that are consistently reactive by initial screening tests


Differentiating between HTLV-1- and HTLV-2-specific IgG antibodies present in spinal fluid

Method Name
A short description of the method used to perform the test

Line Immunoassay (LIA)

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

HTLV -1/-2 Ab Confirmation, CSF

Lists additional common names for a test, as an aid in searching


HTLV confirmation

HTLV-1 confirmation

HTLV-2 confirmation

HTLV Ab confirmation

HTLV-1 Antibody confirmation

HTLV-2 Antibody confirmation

HTLV-1 Ab confirmation

HTLV-2 Ab confirmation

Specimen Type
Describes the specimen type validated for testing


Ordering Guidance

This confirmatory assay should be ordered only on spinal fluid specimens that are consistently reactive by an antihuman T-cell lymphotropic virus 1 and 2 (HTLV-1/-2) screening immunoassay. For an evaluation that includes both screening and confirmation, order HTLVC / Human T-Cell Lymphotropic Virus Types 1 and 2 (HTLV-1/-2) Antibody Screen with Confirmation, Spinal Fluid.


For testing serum specimens, order HTLVL / Human T-Cell Lymphotropic Virus Types I and II (HTLV-I/-II) Antibody Confirmation, Serum.

Necessary Information

Date of collection is required.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Collection Container/Tube: Sterile vial

Specimen Volume: 0.5 mL


If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.2 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

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
CSF Frozen (preferred) 30 days
Refrigerated 14 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Confirmatory detection of human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2)-specific IgG antibodies in spinal fluid specimens that are consistently reactive by initial screening tests


Differentiating between HTLV-1- and HTLV-2-specific IgG antibodies present in spinal fluid

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2) are closely related exogenous human retroviruses. HTLV-1 was first isolated in 1980 from a patient with a cutaneous T-cell lymphoma, while HTLV-2 was identified from a patient with hairy cell leukemia in 1982.


HTLV-1 infection is endemic in southwestern Japan, Caribbean basin, Melanesia, and parts of Africa, where HTLV-1 seroprevalence rates are as high as 15% in the general population. In the United States, the combined HTLV-1 and HTLV-2 seroprevalence rate is about 0.016% among voluntary blood donors. About half of these infected blood donors are infected with HTLV-1, with most of them reporting a history of birth in HTLV-1-endemic countries or sexual contact with persons from the Caribbean or Japan. Smaller percentages report a history of either injection drug use or blood transfusion. Transmission of HTLV-1 occurs from mother to fetus, sexual contact, blood transfusion, and sharing of contaminated needles. Two diseases are known to be caused by HTLV-1 infection: adult T-cell leukemia or lymphoma (ATL) and a chronic degenerative neurologic disease known as HTLV-1-associated myelopathy (HAM) or tropical spastic paraparesis (TSP). Cases of polymyositis, chronic arthropathy, panbronchiolitis, and uveitis have also been reported in HTLV-1-infected patients.


HTLV-2 is prevalent among injection drug users in the United States and in Europe, and more than 80% of HTLV infections in drug users in the United States are due to HTLV-2. HTLV-2 also appears to be endemic in Native American populations, including the Guaymi Indians in Panama and Native Americans in Florida and New Mexico. HTLV-2-infected blood donors most often report either a history of injection drug use or a history of sexual contact with an injection drug user. A smaller percentage of infected individuals report a history of blood transfusion. HTLV-2 is transmitted similarly to HTLV-1, but much less is known about the specific modes and efficiency of transmission of HTLV-2. The virus can be transmitted by transfusion of cellular blood products (whole blood, red blood cells, and platelets). HTLV-2 infection has been associated with hairy-cell leukemia, but definitive evidence is lacking on a viral etiologic role. HTLV-2 has also been linked with neurodegenerative disorders characterized by spastic paraparesis and variable degrees of ataxia.


Infection by these viruses results in the appearance of specific antibodies against the viruses that can be detected by serologic tests such as enzyme immunoassay. For accurate diagnosis of HTLV-1 or HTLV-2 infection, all initial screening test-reactive results should be verified by a confirmatory test, such as Western blot or line immunoassay.

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.


Provides information to assist in interpretation of the test results

Negative confirmatory test results indicate the absence of both human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2)-specific IgG antibodies in spinal fluid and a low probability of an HTLV-1/-2-associated neurologic disorder.


A reactive screening (enzyme immunoassay) result with a negative or indeterminate confirmatory (line immunoassay) test result suggests either a false-reactive screening test result or a seroconverting HTLV infection. Repeat testing with a new specimen can clarify the final infection status. Persistently indeterminate confirmatory test results indicate an absence of HTLV infection.


Positive results for HTLV-1 antibodies indicate the confirmed presence of HTLV-1 IgG antibodies in spinal fluid, based on 2 visible antibody bands that include gp21-I/-II band, or 3 or more bands, and the sum of the gp46-I and p19-I band intensity is greater than the gp46-II band intensity.


Positive results for HTLV-2 antibodies indicate the confirmed presence of HTLV-2 IgG antibodies in spinal fluid, based on 2 visible antibody bands that include gp21-I/-II band, or 3 or more bands, and the gp46-II band intensity is a) greater than the gp46-I band intensity and b) equal or greater than the sum of the gp46-I and p19-I band intensity.


Indeterminate results indicate the presence of the gp21-I/-II band only or combination of any 2 bands without a detectable gp21-I/-II band. Patients with indeterminate test results with known risk factors for HTLV-1 or HTLV-2 infection should undergo repeat confirmatory antibody testing with a new specimen to determine final infection status.


Differentiation of HTLV-1 and HTLV-2 infection is not possible (ie, nontypeable HTLV antibodies) when the band intensity pattern does not meet the criteria of positive HTLV-1 or HTLV-2 antibody band intensity pattern.


Unreadable results indicate the presence of nonspecific background reactivity that is inhibiting the visualization of specific bands on the test strip. Repeat testing with a new specimen is recommended.


Invalid results indicate that nonspecific band reactivity is present. Submit another specimen for retesting, if clinically indicated.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

A negative line immunoassay result does not preclude the possibility of exposure to human T-cell lymphotropic virus types 1 and 2.


Results from this confirmatory assay should always be interpreted together with the reactive screening test result on a given specimen.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Mahieux R, Gessain A: Adult T-cell leukemia/lymphoma and HTLV-I. Curr Hematol Malig Rep. 2007 Oct;2(4):257-264. doi: 10.3390/v8060161. 

2. DeCastro-Costa CM, Araujo AQC, Barreto MM, et al: Proposal for diagnostic criteria of tropical spastic paraparesis / HTLV-I-associated myelopathy (TSP/HAM). AIDS Res Hum Retroviruses. 2006 Oct;22:931-935. doi: 10.1089/aid.2006.22.931.

3. Yamano Y, Sato T: Clinical pathophysiology of human T-lymphotropic virus-type I-associated myelopathy/tropical spastic paraparesis. Front Microbiol. 2012 Nov 9;3:1-10. doi: 10.3389/fmicb.2012.00389.

4. Gessain A, Mahieux R: Tropical spastic paraparesis and HTLV-I associated myelopathy: clinical, epidemiological, virological, and therapeutic aspects. Rev Neurol (Paris). 2012 Mar;168(3):257-269. doi: 10.1016/j.neurol.2011.12.006.

Method Description
Describes how the test is performed and provides a method-specific reference

INNO-LIA HTLV I/II Score is a line immunoassay based on the enzyme immunoassay principle. The assay uses well-defined antigens derived from human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2) immunodominant proteins. The antigens used are either recombinant proteins or synthetic peptides, highly purified and fixed on a nylon membrane strip. The sequences are selected to allow the detection of antibodies with a wide specificity to all known isolates of the HTLV strains. The antigenicity exhibited by these proteins and peptides is either common to both HTLV-1 and HTLV-2, or type-specific to 1 of the 2 viruses to allow confirmation and discrimination in a single assay. Two gag (p19-I/II, p24-I/II) and 2 env (gp46-I/II, gp21-I/II) bands are applied as non-type-specific antigens, which are used to confirm the presence of antibodies against HTLV-1/2. The type-specific antigens for HTLV-1 (gag p19-I, env gp46-I) and for HTLV-2 (env gp46-II) are applied to differentiate between HTLV-1 and HTLV-2 infections. In addition, 4 control lines are coated: 1 negative control (streptavidin), and 3 positive control lines: a strong (antihuman IgG), a moderate (human IgG), and a weak (human IgG) line.


A test sample is incubated in a test trough together with the multiple antigen-coated strip. Specific HTLV antibodies, if present in the sample, will bind to the HTLV antigen lines on the strip. Subsequently, goat-antihuman IgG labeled with alkaline phosphatase is added and will bind to any HTLV antigen-antibody complex previously formed. Incubation with a chromogenic substrate produces a dark brown color in proportion to the amount of specific antibodies present in the sample. The color development is stopped with sulfuric acid. If the sample contains no HTLV-specific antibodies, only a low background color develops.(Unpublished Mayo method)

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.


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.

2 to 15 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


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  • Prospective clients should contact their Regional Manager. 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 was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

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.


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
HTLLC HTLV -1/-2 Ab Confirmation, CSF 93744-1
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.
604935 HTLV-1/-2 Ab Confirmation, CSF 93745-8
604945 HTLV-1/-2 Bands 93743-3
604946 HTLV-1/-2 Discrimination 93742-5

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports