Lecture 9-rheumatoid factor

mr-said warsame nur

1. Rheumatoid Factor

2. Introduction Rheumatoid factors are antibodies with specificity for antigen determinants on the Fc fragment of human or certain animal IgG . They’re associated with IgG , IgM & IgA. IgG & IgM rheumatoid factors are the most common . During some disease of a joint, rheumatoid arthritis, an IgG antibody is produced following to its production the antibody become altered for unknown reason, against this altered antibody a second antibody (anti antibody) is produced which is known as antigammaglobulin antibody.

3. Test for Rheumatoid arthritis Rapid latex agglutination Principle : The test is based on the reaction between patient antibodies in the serum, known as the rheumatoid factor; and an antigen derived from gamma globulin. If rheumatoid factors are present in the serum, macroscopic agglutination will be visible when the latex reagent is mixed with the serum. Specimen: Serum

4. Reagents & materials required Latex reagent Glycine saline buffer Capillary pipette Applicator stick Glass slide Additional required equipment Timer Test tubes Serologic pipette Positive control Negative control

5. PROCEDURE A. FOR QUALITATIVE TEST

6. PROCEDURE

7. Reporting results Positive reaction: agglutination of the latex suspension indicates the presence of rheumatoid factor in the specimen. Negative reaction: absence of visible agglutination.

8. STORAGE AND STABILITY

9. QUALITY CONTROL RF Positive and Negative Control should be included in each test batch. Acceptable performance is indicated when a uniform milky suspension with no agglutination is observed with the RF Negative Control and agglutination with large aggregates is observed with the RF Positive Control.

10. LIMITATIONS Reaction time is critical. If reaction time exceeds 2 minutes , drying of the reaction mixture may cause false positive result . Increased levels of RF may be found in some diseases other than rheumatoid arthritis such as infectious mononucleosis. Certain patients with rheumatoid arthritis will not have the RF present in their serum.