Measurement of rheumatoid factors in the non-treated and 2-ME treated sera by Laser Nephelometer

Abstract

Measurement of rheumatoid factor (RF) has been broadly used for evaluation of rheumatoid arthritis and the other diseases. For the detection of RF, passive hemaglutination test and Latex fixation test (LFT) are mainly used. However, they sometimes give controversial results under the influence of C_??_ and excess amount of γ-globulin. In this study described here, RF activity was measured in Laser Nephelometer (LN) by using human heat aggregated IgG as a antigen and compared the titer in LFT. By LFT and LN, RF activity in fresh sera found to have no differences, whereas RF activity in the long standing sera or particularly in the longstanding hyper γ-globulinemic sera found to be significantly increased in the LFT, comparing its activity in the fresh serum. But LN showed almost same results in the RF activity in both fresh or longstanding sera.Positivity of RF activity in sera and joint fluids from patients with rheumatoid arthritis was 79% and 60% in LN and 82% and 64% in LFT, respectively. The RF activity in the 2-mercapto-ethanol (2-ME) treated sera and-joint fluids found to have 21% and 24% in LN and 34% and 33% in LFT, respectively. The RF activity in the 2-ME treated LFT-positive sera from the patients with liver cirrhosis found to have 3% in LN and 11% in LFT.Thus, the RF activity measured by LN seems to be more accurate than that measured by LFT. Furthermore, these results suggested that the RF activity measured by LN in 2-ME treated sera indicated to be non-IgM-RF, presumably mainly containing IgG-RF.