The pattern of anti-immunoglobulin activities in serum, pleural, and synovial fluids.

Abstract

Abstract A number of surveys on the occurrence of rheumatoid factors (RF) in nonrheumatoid sera, pleural, and synovial effusions suggests a lack of diagnostic specificity in many of the commonly employed RF test systems. Sera matched with effusion fluids of 70 patients were tested in 4 commonly used RF test systems standardized against an International RF Reference Standard. Although there were significant positive results in both the rheumatoid and nonrheumatoid specimens, the pattern of reactivity suggested classical RF in the former, but a high incidence of anti-antibody in the latter. Inhibition tests confirmed this impression. Anti-antibody was responsible for 88 per cent of our nonrheumatoid RF-positive tests and of these, 79 per cent occurred in our pleural effusion patients. Moreover, this study shows that the diagnostic specificity of RF testing is improved when agglutination inhibition techniques are used to differentiate RF from other immune, non-RF, antiglobulin agglutinators such as anti-Gm factors and anti-antibodies. Thus, in addition to eliminating nonimmune agglutinations by heat decomplementation of all specimens and hyaluronidase treatment of the most viscous synovial effusions, agglutination specificity challenges for RF and non-RF immune factors using pooled native and heat-aggregated γ-globulin aid in further characterizing the source as rheumatoid or nonrheumatoid.