Presentation:

RF LATEX
50 Test Ref.: 40120 RF
100 Test Ref.: 40121
Store: 2 - 8º C.
Slide agglutination
Diagnostic reagent for qualitative measurement of MATERIAL REQUIRED BUT NOT PROVIDED CLINICAL SIGNIFICANCE
Rheumatoid Factors (RF). - Mechanical rotator with adjustable speed at 80-100 r.p.m. Rheumatoid factors are a group of antibodies directed to
- Vortex mixer. determinants in the Fc portion of the immunoglobulin G molecule.
Only for in vitro use in clinical laboratory (IVD) - Pippetes 50 µL. Although rheumatoid factors are found in a number of rheumatoid
disorders, such as systemic lupus erythematosus (SLE) and
TEST SUMMARY General laboratory equipment Sjögren’s syndrome, as well as in non-rheumatic conditions, its
The RF-latex is an slide agglutination test for the qualitative and semi- central role in clinic lies its utility as an aid in the diagnosis of
quantitative detection of rheumatoid factors in human serum. TEST PROCEDURE rheumatoid arthritis (RA). An study of the “American College of
Latex particles coated with human gamma globulin are agglutinated when Qualitative method Rheumatology” shows that the 80.4% of RA patients were RF
mixed with samples containing RF. 1. Allow the reagents and samples to reach room temperature. The positive.
REAGENTS COMPOSITION sensitivity of the test may be reduced at low temperatures.
2. Place 50 µL of the sample and one drop of each Positive and Clinical diagnosis should not be made on a single test result; it should
Latex particles coated with human gamma globulin, integrate clinical and other laboratory data.
Latex Negative controls into separate circles on the slide test.
pH, 8.2. Preservative.
3. Mix the RF-latex reagent rigorously or on a vortex mixer before
Control (+) Human serum with a RF concentration > 30 IU/mL. using and add one drop (50 µL) next to the sample to be tested. REAGENT PERFORMANCE
Red cap Preservative 4. Mix the drops with a stirrer, spreading them over the entire – Analytical sensitivity: 8 (6-16) IU/mL, under the described assay
Control (-) surface of the circle. Use different stirrers for each sample. conditions
Animal serum. Preservative – Prozone effect: No prozone effect was detected up to 1500 IU/mL.
Blue cap 5. Place the slide on a mechanical rotator at 80-100 r.p.m. for 2
minutes. False positive results could appear if the test is read later – Diagnostic sensitivity: 100 %
PRECAUTIONS than two minutes. – Diagnostic specificity: 100 %
Components from human origin have been tested and found to be
Semi-quantitative method The diagnostic sensitivity and specificity have been obtained using
negative for the presence of HBsAg, HCV, and antibody to HIV (1/2).
1. Make serial two-fold dilutions of the sample in 9-g/L saline 139 samples compared with the same method of a competitor.
However, handle cautiously as potentially infectious.
solutions.
Good laboratory safety practices should be followed when handling INTERFERING SUBSTANCES
2. Proceed for each dilution as in the qualitative method.
laboratory reagents or human samples. Bilirubin (20 mg/dL), hemoglobin (10 g/L), and lipids (10 g/L), do not
READING AND INTERPRETATION interfere. Other substances may interfere6.
REAGENT PREPARATION AND STABILITY Examine macroscopically the presence or absence of visible
All the kit components are ready to use, and will remain stable until the NOTES
agglutination immediately after removing the slide from the rotator.
expiration date printed on the label, when stored tightly closed at 2-8ºC 1. Results obtained with a latex method do not compare with those
The presence of agglutination indicates a RF concentration equal or
and contaminations are prevented during their use. obtained with Waaler Rose test. Differences in the results
greater than 8 IU/mL. (Note 1) .
Do not freeze; frozen reagents could change the functionality of the test. between methods do not reflect differences in the ability to
The titter, in the semi-quantitative method, is defined as the highest
Always keep vials in vertical position. If the position is changed, gently detect RF.
dilution showing a positive result.
mix to dissolve aggregates that may be present. LIMITATIONS OF THE PROCEDURE
Reagents deterioration: CALCULATIONS
– The incidence of false positive results is about 3-5 %. Individuals
- Presence of particles and turbidity. The approximate RF concentration in the patient sample is calculated suffering from infectious mononucleosis, hepatitis, syphilis as well
as follows: as elderly people may give positive results.
All the reagents of the kit are stable up to the end of the indicated month
and year of expiry. Store tightly closed at 2-8ºC. Do not use reagents over
8 x RF Titter = IU/mL. – Diagnosis should not be solely based on the results of latex
the expiration date. method but also should be complemented with a Waaler Rose test
QUALITY CONTROL
Positive and Negative controls are recommended to monitor the along with the clinical examination.
CALIBRATION
The RF-latex sensitivity is calibrated against the RF International performance of test procedure, as well as a comparative pattern for a BIBLIOGRAPHY
Calibrator from WHO (WHO 64/2 Rheumatoid Arthritis Serum). better results interpretation. 1. Robert W Dorner et al. Clinic clinical Acta 1987; 167: 1 – 21.
All result different from the negative control result, will be considered 2. Frederick Wolfe et al. Arthritis and Rheumatism 1991; 34: 951-
SPECIMEN as a positive. 960.
Fresh serum. Stable 7 days at 2-8º C or 3 months at –20º C. Serum controls RF are recommended for internal quality control. Each 3. Robert H Shmerling et al. The American Journal of Medicine
The samples with particles or fibrin should be centrifuged to eliminate laboratory should establish its own Quality Control scheme and 1991; 91: 528 – 534.
them. Do not use haemolysed or lipemic samples. corrective actions.
4. Adalbert F. Schubart et al. The New England Journal of
Discard contaminated specimen Medicine 1959; 261: 363 – 368.
REFERENCE VALUES 5. Charles M. Plotz 1956; American Journal of Medicine; 21:893
Up to 8 IU/mL. – 896.
It is suggested that each laboratory establish its own reference range.
6. Young DS. Effects of drugs on clinical laboratory test, 4th ed.
AACC Press, 1995.

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