What is Rheumatoid Factor (RF) and How to Use Rheumatoid Factor (RF) Rapid Test Kit?
Rheumatoid factor (RF) testing is currently among the most common diagnostic methods that assist medical professionals in the diagnosis of rheumatoid arthritis (RA) and various other connective tissue diseases affecting human health. Although rheumatoid factors were discovered more than 70 years ago, much is left to discover concerning the mechanisms underlying their production, physiological role, and pathological impact in relation to different autoimmune and non-autoimmune diseases. With the development of rapid testing methods such as antibody assays and latex agglutination assays, the detection of rheumatoid factor (RF) has become quicker, accessible, and more convenient than ever. Read along to learn more about rheumatoid factor (RF), rheumatoid arthritis (RA), and how the Rheumatoid Factor (RF) Test Kit is used to detect rheumatoid factor (RF) to assist the diagnosis and prognosis of rheumatoid arthritis (RA).
What is Rheumatoid Factor (RF)?
Rheumatoid factors (RF) are antibodies directed against the Fc region of immunoglobulin G. Rheumatoid factors (RF) have been named after their initial discovery in 1948 in patients with rheumatoid arthritis (RA). While they were named after their association with rheumatoid arthritis (RA), rheumatoid factors (RF) have been found in patients with a variety of autoimmune and infectious diseases of concern, including Sjogren’s syndrome, arthritis, rheumatic fever, pulmonary tuberculosis, bacterial endocarditis, and syphilis. However, while their occurrence does not exceed 2 or 3% in conditions such as arthritis or rheumatic fever, rheumatoid factors (RF) can be found in up to 70-100% of all cases of definite rheumatoid arthritis (RA). Accordingly, rheumatoid factors (RF) are widely considered useful markers for the diagnosis of suspected rheumatoid arthritis (RA).
What is Rheumatoid Arthritis (RA)?
Rheumatoid arthritis (RA) is a chronic autoimmune disorder that emerges when the immune system attacks the healthy cells forming the tissue lining around the joints known as synovium. As an inflammatory form of arthritis, it leads to inflammation in the synovium and causes the synovium to grow thicker. As a result, patients may get swollen or red joints, experience pain or tenderness around the joint area, and have difficulty moving their joints. Accordingly, the resulting tissue damage may lead to long-lasting pain, lack of balance, and deformity. Although rheumatoid arthritis (RA) most commonly targets the joints in the hands, wrists, and knees, it can also affect various other tissues throughout the body and cause issues in different organs, including the lungs, heart, or eyes. Rheumatoid arthritis (RA) typically presents with a feeling of pain, aching, stiffness, and tenderness in more than one joint. These symptoms may be coupled with weight loss, fever, fatigue, tiredness, and weakness. The symptoms are often mirrored on both sides of the body and experienced in flares. There is currently no definitive cure for rheumatoid arthritis (RA). However, the inflammation can effectively be suppressed, and the symptoms can be managed with early diagnosis and effective treatment.
What is the Rheumatoid Factor (RF) Rapid Test Kit?
There is a wide array of different methods available for the detection of rheumatoid factors (RF), such as nephelometry, turbidimetry, and agglutination of gamma globulin-coated latex particles or erythrocytes. However, antibody detection and latex agglutination methods are among the most common rapid testing options. Among these, antibody-based methods often come in the form of rapid monochromatic assays in lateral flow test format. These assays detect the presence of IgA, IgM, or IgG antibodies produced in reaction to rheumatoid factors (RF) in human serum or plasma and deliver qualitative results in just a few minutes. Latex agglutination tests, on the other hand, employ polystyrene particles coated with a layer of absorbed human gamma globulin to detect rheumatoid factor (RF) that may be present within a serum sample. If rheumatoid factor (RF) is present in a tested serum sample, the globulin in serum reacts with the corresponding lgG bound to finely dispersed polystyrene latex particles to produce a visible agglutination of the biologically inert latex particles.
How to Use the Rheumatoid Factor (RF) Rapid Test Kit?
Prior to performing a rapid antibody test or latex agglutination test for the detection of rheumatoid factor (RF), all components of the test kit have to be allowed to reach room temperature. If the test at hand is rapid antibody testing, the test procedure requires the transfer of the collected serum or plasma sample to a buffer tube via a dropper or micropipette. Next, the vial is shaken thoroughly to ensure that the collected sample and the diluents mix well. Then, the test cassette is removed from its sealed package to be placed on a clean and flat surface. Finally, a few drops of the sample-buffer solution are added into the sample well (S) on the cassette and a timer is started. The results should be read within the reaction time specified in the manual, which is often between 10 to 15 minutes. The presence of the test line (T) and control line (C) indicates that the plasma or serum sample tested positive for rheumatoid factor (RF), while the presence of only the control line (C) indicates a negative result. If the control line is absent at the end of the specified reaction time, the results are considered invalid, and the procedure should be repeated with a new kit.
If the kit at hand is a latex agglutination test, on the other hand, the procedure begins by shaking the provided latex reagent gently and aspirating the dropper a few times to acquire a thorough mixing. Next, one drop of the collected serum sample is placed into one of the circles on the test slide. One drop of positive control serum and one drop of negative control serum is also added into two other circles. With the help of the provided dropper, one drop of the latex reagent is placed next to the serum samples in the circles on the slide. Then, each specimen is mixed with the added latex reagent via a disposable stirrer, and the solution is spread over the entire surface of each circle. The slide is rotated for 2 minutes at 80 to 100 revolutions per minute. Finally, the slide is examined under a bright light source for agglutination. The presence of agglutination indicates that the sample tested positive for rheumatoid factor (RF).
Alhabbab, R.Y. (2018). Rheumatoid Factor (RF). In: Basic Serological Testing. Techniques in Life Science and Biomedicine for the Non-Expert. Springer, Cham. https://doi.org/10.1007/978-3-319-77694-1_7