ANA DETECTION Flashcards
Materials
⤳ SLE latex suspension
⤳ Black test cards
⤳ Mechanical rotator
⤳ Positive and Negative Controls
⤳ Disposable stirrers
Principle of the test
Passive Latex Agglutination
Meaning of ELISA
Enzyme-Linked Immunosorbent Assay
Meaning of CLIA
Chemiluminescence immunoassay
These assays can testfrom a broad range of antibodies if multiple nuclear antigens are coated onto a single test well, or for a specific
ANAs if each well is coated with a single antigen.
ELISA and CLIA
ELISA & CLIA depends on?
Depends on the type of nuclear antigen loaded on the well
Capable of detecting various diseases
Multiple nuclear antigens
Capable of detecting single or specific diseases
Specific nuclear antigen
These antigens use in commercial kits are derived from
Tissue extracts or produced by recombinant technology
It is used to screen for the presence of anas in addition to identifying specific anas
ELISA methods
There is a large variation in the performance of test produced by different manufacturers, which is influenced by the
Antigen preparation used
One study found sensitivities of elisa assays ranging from
69% to 98%
Specificities of elisa ranges from
81% to 98% when they were compared with IFF ANA method
Proportion of patients with a disease who test positive
Sensitivity
Proportion of patients without a disease who test negative
Specificity
If 100 patients known to have a disease were tested, and 43 test positive, then the test has 43% sensitivity. If 100 with no disease are tested and 96 return a completely negative result, then the test has 96% specificity.
True
Reagents
Ana reagent
Positive and negative control reagents
Wells
Qualitative method (screening) procedure
- Bring all reagents to room temperature and mix gently prior to use.
- Place the following on separate divisions of the same black test card.
- Place a drop of undiluted serum into the circles of the test slides
⤳ Patient’s Serum: 1 drop
⤳ Positive Control: 1 drop
⤳ Negative Control: 1 drop - Add 1 drop of SLE Latex reagent to each sample on the black test card.
- Mix with the flat end of the pipette/mixer and spread fluid evenly covering the entire
diameter of the test circle. - Tilt the slide back and forth slowly for 3 minutes while observing for agglutination.
- Observe and Interpret results.
The test is considered as NEGATIVE when no difference in agglutination is observed between the specimen and negative control and POSITIVE sera must show distinct agglutination within _ minutes.
3
Agglutination indicates the level of ___ (especially anti-DNP) in the
range commonly found in the SLE.
antinuclear antibody
Findings in the sensitivity studies suggest that immunoassays may miss a significant proportion of ANA-positive patients and also yield a significant number of _____
false positive results.
Based on such studies, the ___ has recommended that the IIF test remains the gold standard for ANA testing and that clinical laboratories should specify the method they use when they are reporting the result.
ACR (American College of Rheumatology)