Introduction
• Rheumatoid factorsare 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 Rheumatoidarthritis
• 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
Reporting results
• Positivereaction: agglutination of the latex
suspension indicates the presence of
rheumatoid factor in the specimen. Negative
reaction: absence of visible agglutination.
QUALITY CONTROL
• RFPositive 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.
12.
LIMITATIONS
• Reaction timeis 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.
