Rheumatoid arthritis test to detect the presence of Rheumatoid Factors

Rheumatoid arthritis abbreviated RA is a chronic and inflammatory (inflammatory arthritis) disease of flexible (synovial) joints (joint pain). During this disorder, the synovial lymphocytes produces an abnormal Immunoglobulin G and in response to this the host immune system generates Immunoglobulin M and these are called Rheumatoid factors (RF). These antibodies are generated against one’s own tissue and are called autoantibodies and for this reason RA is considered as a systemic autoimmune disease.Through a blood test the presence of RF can be detected and consequently rheumatoid arthritis diagnosis. Therefore  rheumatoid arthritis test is to detect the presence of Rheumatoid Factors (RF) which are produced during Rheumatoid arthritis  

Principle of rheumatoid arthritis blood test

An agglutination reaction is  the clumping together of antigen-bearing cells, microorganisms or particles in the presence of specific antibodies (agglutinins) in a suspension. Agglutination reaction time is  shorter as compared to other antigen-antibody interactions.

This is a Latex agglutination test which makes use of latex particles which are built from different organic materials to a desired diameter, and may be functionalized with chemical groups to facilitate attachment of molecules. In this method the patient’s blood sample is mixed with tiny latex beads covered with human antibodies (IgG). The latex beads clump or agglutinate if rheumatoid factor (IgM RF) is present.  

Rheumatoid arthritis principle
Rheumatoid arthritis principle

Reagent required for Rheumatoid arthritis(RA Test Kit)

Materials Provided QuantityStorage Temperature
Latex reagent 1.5 ml 2-80 C
Positive control 0.2 ml 2-80 C
Negative control 0.2 ml 2-80 C
Disposable Agglutination Cards——————————
Disposable Mixing Sticks——————————

Materials required for Rheumatoid arthritis Test

  • Test Serum Sample
  • Micropipettes
  • Tips
  • Gloves
Also read  Widal Slide and tube test principle and result interpretation

How to perform Rheumatoid arthritis Test 

Please follow the instruction of manual provided with test kits and Allow all reagents to reach room temperature  and mix well before using

  1. Pipette 10µl of test serum sample on one of the latex disposable slide circle
  2. Pipette 10 µl of Positive and Negative control each on other circles.
  3. Now add 25 µl of Latex reagent to all these three circles (Test,Positive and Negative control).
  4. Avoid touching the liquid on the slide with the reagent dropper tip,this may result to contamination of the whole reagent
  5. Using the disposable mixing sticks mix all the contents uniformly over the entire circles of  each slide.
  6. Now rock the slide gently, back and forth for 2 minutes. Then observe for agglutination.  
Rheumatoid arthritis procedure

Rheumatoid arthritis procedure

Observation and Result of rheumatoid arthritis test

After mixing the  Latex reagent with Positive control, Negative control and Test sample separately observe for visible agglutination reaction as shown below

Rheumatoid arthritis result

Rheumatoid arthritis result
  • Circle 1: Positive Control
  • Circle 2: Test sample
  • Circle 3: Negative Control

How to Interpret of rheumatoid arthritis test

Agglutination of latex particles is considered a positive reaction, as indicated above in Slide 1 and 2 (Test and Positive control) indicating the presence of rheumatoid factor at a significant and detectable level. Slide 3 is Negative control with no agglutination hence no rheumatoid factors present.

Possible Limitation of Rheumatoid arthritis Test

Problem Possible Cause Solution
False positive result  -The reagents were mixed with each other



-Incubated for a longer time  
-Ensure that the reagents are added properly onto the respective well without spilling to the sides

-The results should be read within the time period mentioned in the brochure
No agglutination observed  The reagents are not stored under proper conditionsEnsure that the latex reagent, positive and negative control are stored in refrigerator (2-8 °C)  

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About the Author: Arthur Westmann

DEFFE ARTHUR (AMOEBAMANN) is the founder and author of MLTGEEKS and MLTEXPO.He’s from Cameroon and is currently a Final year State Medical Laboratory Technician (MLT MA). Beyond lab works, he’s a passionate internet user with a keen interest in web design and blogging. Furthermore He likes traveling, hanging around with friends and social networking to do in his spare time.

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