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4. Mix with separate mixing sticks, spreading the mixture uniformly over the entire reaction circle. 5. Immediately start a stopwatch. Rock the slide gently, back and forth, observing for agglutination

  Anti-DNP is present in high titers in the serum of

majority of SLE patients with active disease but is

present occasionally in remission states. Although

anti-DNP is found exclusively in SLE, only low titers

may be detected in diseases such as chronic hepatitis,

periarteritis nodosa, dermatomyositis, scleroderma and

drug hypersensitivity.

Reagent

The Rhelax SLE reagent is a ready-to-use uniform

suspension of polystyrene latex particles coated with

deoxyribonucleoprotein (DNP). Each batch of reagents

undergoes rigorous quality control at various stages of

manufacture for its specificity, sensitivity and performance.

Reagent Storage and Stability

Store the reagent at 2 to 8°C. Do not freeze. The shelf-life

of the reagent is as per the expiry date mentioned on the

reagent vial label.

Principle

Latex particles coated with DNP will agglutinate when

mixed with serum containing anti-DNP. No agglutination

indicates absence of anti-DNP in the serum.

Note

1. In vitro diagnostic reagent for laboratory and

professional use only. Not for medicinal use.

2. All the components derived from human source have

been tested for HBsAg and anti-HIV antibody and

are found to be non-reactive. However, handle the

material as if infectious.

3. The reagents contain sodium azide 0.1% as preservative.

Avoid contact with skin and mucosa. On disposal,

flush with large quantities of water.

4. The reagent can be damaged due to microbial

contamination or exposure to extreme temperatures.

It is recommended that the performance of the reagent

be verified with the positive and negative controls

provided with the kit.

5. Shake the latex reagent well before use to disperse

the latex particles uniformly and to improve test

readability.

6. Only a clean and dry glass slide must be used. Clean

the slide with distilled water and wipe dry.

Sample Collection and Preparation

No special preparation of the patient is required prior to

sample collection by approved techniques. Use fresh clear

serum samples. In case of delay in testing, store the serum

samples at 2 to 8°C for up to 72 hours. For longer storage,

freeze the serum. However, repeated freezing and thawing

of samples should be avoided.

Material Provided with the Kit

Reagent Pack

Rhelax SLE latex reagent, positive control, negative control.

660 Concise Book of Medical Laboratory Technology: Methods and Interpretations Accessories Pack

Glass slide with six reaction circles, mixing sticks, rubber

teats, sample dispensing pipettes.

Additional Material Required

Test tube (10 × 75 mm), Pipettes, isotonic saline, stopwatch,

direct light source.

Test Procedure

Bring all reagents and samples to room temperature

before use.

Qualitative Method

1. Place one drop of sample to be tested onto one of

the reaction circles of the glass slide using a sample

dispensing pipette provided with the kit.

2. Place one drop of positive and negative control onto

separate reaction circles of the glass slide.

3. Gently shake the latex reagent and add one drop to

each sample and control taken on the slide.

4. Mix with separate mixing sticks, spreading the mixture

uniformly over the entire reaction circle.

5. Immediately start a stopwatch. Rock the slide

gently, back and forth, observing for agglutination

macroscopically at 3 minutes.

Semiquantitative Method

1. Using isotonic saline prepare serial dilutions of the

serum sample 1:2, 1:4, 1:8, 1:16, 1:32.

2. Place each dilution of the serum sample onto separate

reaction circles of the slide.

SEROLOGICAL DIAGNOSIS RHEUMATIC DISORDERS WITH LATEX AGGLUTINATION TESTS RF, CRP, ASL

Spectrum Probable diagnosis Further test indicated

Latex agglutination tests

CRP ASL RF

– + – Rheumatic fever Anti-streptolysin titer determination

+ + – Acute rheumatic fever ADNase B, AHy, ANADase

– – + Chronic polyarthritis (CP) Quantitative RF determination

+ – + Inflammation in acute attack Quantitative RF determination

+ – – Acute inflammatory (CP) (early stage) Quantitative RF determination

– – + Lupus erythematosus (LE),

Polyarteritis nodosa,

Dermatomyositis,

Polymyositis, scleroderma

ANA (antinuclear Ab) Anti-ds-DNA

against native double filament

(+)

Seronegative chronic polyarthritis

(e.g. juvenile arthritis)

Behçet’s disease

Collagen/MCTD (mixed connective

tissue disease)

Reiter’s disease

Psoriasis

LE

Pseudo-LE (drug induced)

ANA/HLA B-27

HLA B 27

ANA, Anti-ds-DNA

HLA B 27, Yersinia antibody detection

-

ANA

AMA (antimitochondrial antibody)

+ – – Inflammatory-degenerative

rheumatic disorders

Gout (acute attack)

Reactive arthritis

(after infection)

Uric acid

Gonococcal detection, virus

serology (e.g. Rubella infection)

+ – + By chronic appearance

of age and other

inflammatory conditions

Quantitative RF

– = Negative, + = Positive, (+) = Weakly positive

Serology/Immunology 661

3. Add one drop of well-mixed latex reagent to each

dilution of the sample on the slide.

4. Mix with separate mixing sticks, spreading the mixture

uniformly over the entire reaction circle.

5. Immediately start a stopwatch. Rock the slide

gently, back and forth, observing for agglutination

macroscopically at 3 minutes.

Interpretation of Results

Qualitative Method

Agglutination is a positive test result and indicates

presence of anti-DNP in the test specimen.

No agglutination is a negative test result and indicates

absence of anti-DNP in the test specimen.

Semiquantitative Method

The titer of the serum is the reciprocal of the highest

dilution which gives agglutination.

Remarks

1. Markedly lipemic, hemolyzed and contaminated

serum samples could produce nonspecific results.

2. Use of plasma rather than serum can lead to false

positive results.

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