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Test ID: CDCOM    
Celiac Disease Comprehensive Cascade

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

Immunoglobulin A (IgA):

Total IgA levels are measured by immunonephelometry. Rabbit antisera that specifically recognizes human IgA is added to the patient sample. Immune complexes form between the human IgA and the rabbit immunoglobulins; the immune complexes scatter light that is passed through the sample. The intensity of the scattered light is related to the amount of human IgA in the sample. The concentration of IgA in the sample is calculated from a multipoint calibration curve.(Behring Nephelometer II Operations Instruction Manual. Dade Behring, Inc. Newark, DE 19714)

 

HLA-DQ Typing:

LABType applies Luminex technology to the reverse SSO DNA typing method. First, target DNA is PCR-amplified using a group-specific primer. The PCR product is biotinylated, which allows it to be detected using R-Phycoerythrin-conjugated streptavidin. The PCR product is denatured and allowed to rehybridize to complementary DNA probes conjugated to fluorescently coded microspheres. A flow analyzer, identifies the fluorescent intensity of phycoerythrin on each microsphere. The HLA Class II allele or allele groups of the sample is determined by the positive and negative bead ID's using a computer software program. The assignment of the HLA typing is based on the reaction pattern compared to patterns associated with published HLA gene sequences.(Package insert: One Lambda, LABType SSO Typing)

 

Tissue Transglutaminase (tTG) Antibody, IgA/IgG:

IgA and IgG antibodies to tTG are detected by enzyme-linked immunosorbent assay (ELISA). Recombinant human tTG antigen expressed in Escherichia coli is adsorbed to wells of a microtiter plate under conditions that preserve the native state of the antigen. Diluted patient sera are added to the microtiter plate wells under conditions that allow binding of the antibodies to the tTG antigen. Unbound sample constituents are washed away and horseradish peroxidase (HRP)-labeled antihuman IgA or IgG antibody conjugate is added to each well. After a second incubation, unbound HRP-label is removed and bound conjugate is detected by adding tetramethylbenzidine (TMB) chromogenic substrate. After a final incubation, colored product is measured spectrophotometrically; the absorbance of the patient sample is compared to the positive calibrator. The absorbance is directly proportional to the level of IgA or IgG antibodies to tTG, which is expressed in arbitrary units.(QUANTA Lite R h-tTG IgA and IgG. Inova Diagnostics, Inc. San Diego, CA, 92131)

 

Gliadin (Deamidated) Antibody, IgA/IgG:

IgA and IgG antibodies to deamidated gliadin peptides are detected by enzyme-linked immunosorbent assay (ELISA). Purified peptides are adsorbed to wells of a microtiter plate under conditions that preserve the native state of the antigen. Diluted patient sera are added to the microtiter plate wells under conditions that allow binding of the antibodies to the deamidated gliadin peptides. Unbound sample constituents are washed away and HRP-labeled antihuman IgA or IgG antibody conjugate is added to each well. After a second incubation, unbound HRP-label is removed and bound conjugate is detected by adding tetramethylbenzidine (TMB) chromogenic substrate. After a final incubation, colored product is measured spectrophotometrically; the absorbance of the patient sample is compared to the positive calibrator. The absorbance is directly proportional to the level of IgA or IgG antibodies to deamidated gliadin peptides, which is expressed in arbitrary units.(QUANTA Lite Gliadin IgA II and IgG II. INOVA Diagnostics, Inc. San Diego, CA, 92131)

 

Endomysial (EMA) Antibody, IgA:

IgA endomysial antibodies are detected by indirect immunofluorescence assay (IFA). Frozen sections of rhesus monkey esophagus substrate are overlaid with dilutions of patient sera and incubated. After washing, the slides are overlaid with fluorescein-conjugated IgA antisera and incubated. After a final washing, the slides are analyzed through fluorescence microscopy.(Chorzelski TP, Beutner EH, Sulet J, et al: IgA anti-endomysium antibody: A new immunological marker of dermatitis herpetiformis and coeliac disease. Br J Dermatol 1984;111:395-402)

Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

IgA: Monday through Saturday; 3 p.m.

HLA-DQ Typing: Monday through Friday; 7:30 a.m.-5:00 p.m.

tTG IgA: Monday through Saturday;  p.m.

Endomysial antibodies: Monday through Friday; 7 a.m.-5 p.m.

Gliadin IgA: Monday through Saturday; 3 p.m.

tTG IgG: Monday through Saturday;  p.m.

Gliadin IgG: Monday through Saturday; 3 p.m.

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

7 days (Max Lab time = 14 days)

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

See individual unit codes

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

Rochester