The RF latex test kit ( Serology kit) is intensed for the qualitative and semi-quantitative measurement of RF in human serum.

INTRODUCTION
Rheumatoid factors (RF) are antibodies directed against antigenic sites in the Fc fragment of human and animal IgG. Their frequent occurrence in rheumatoid arthritis makes them useful for diagnosis and monitoring of the disease. 1,2

One method used for rheumatoid factor detection is based on the ability of rheumatoid arthritis sera to agglutinate sensitized sheep red cells, as observed by Waaler3 and Rose. 4 A more sensitive reagent consisting of biologically inert latex beads coated with human gamma globulin was later described by Singer and Plotz. 5 The RF kit is based on the principle of latex agglutination assay by Singer and Plotz. 5 The major advantage of this method is rapid performance (3 minute reaction time) and lack of heterophile antibody interference.

PRINCIPLE
The RF reagent is a suspension of polystyrene latex particles sensitized with specially prepared human IgG. The reagent is based on an immunological reaction between human IgG bound to biologically inert latex particles and rheumatoid factors in the test specimen. When serum containing rheumatoid factors is mixed with the latex reagent, visible agglutination occurs. The RF latex reagent sensitivity has been adjusted to detect a minimum of 8 IU/mL of rheumatoid factors according with the WHO International Standard without previous sample dilution.