[Recent problems in laboratory tests for rheumatoid factor].
Conventional laboratory tests for detection of rheumatoid factor (RF) have changed because of the demands of recently-developed rheumatologic therapy. Quantitative analysis of the RA test by turbidimetry and nepherometry of latex agglutination or turbidity immunoassay (TIA) was recently introduced and popularized in Japan. Although the RF standards provided by WHO have become quite common, RF values obtained by quantitative analysis in various laboratories are not consistent with each other. We established a murine monoclonal rheumatoid factor (mRF) and recommend this as the national RF standard to replace the WHO standard. We believe that the RF titer of a clinical serum should be expressed as the corresponding concentration of mRF which agglutinates IgG-coated latex to the same degree as the serum in quantitative analysis. When possible, inconsistency of RF titers among various laboratories must be eliminated. Detection of IgG-RF has recently been included among tests available for medical insurance reimbursement. The test is very useful to diagnose malignant rheumatoid arthritis associated with vascular damage and extra-articular disorders.
Department of Laboratory Medicine, Faculty of Medicine, University of Tokyo.
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Yoshinoya
D006801:Humans; D008722:Methods; D012217:Rheumatoid Factor / Q000032:analysis*
D012217:Rheumatoid Factor