IGG-RHEUMATOID, IGM-RHEUMATOID AND IGA-RHEUMATOID FACTORS IN HEALTHY-ADULTS AND RHEUMATOID PATIENTS DETERMINED BY AN INDIRECT IMMUNOFLUORESCENCE METHOD

  • 1 January 1979
    • journal article
    • research article
    • Vol. 8  (1) , 1-9
Abstract
Sera from 173 healthy adults and 55 rheumatoid patients were studied for Ig[immunoglobulin]G-, IgM- and IgA-rheumatoid factors (RF) by a modification of Este''s indirect immunofluorescence method. Rabbit IgG bound to smeared sheep red cells was used as antigen. With each serum tested a smear of non-sensitized cells was used as control antigen. Anti-IgG of the sera studied, binding to the antigen, was demonstrated by fluorescein-conjugated antisera, monospecific for .gamma., .mu. and .alpha. chains, and not containing antibodies to sheep erythrocytes or rabbit IgG. Positive reactions were obtained with IgG as antigen, but not with the F(ab'')2 fragment. The sera tested were treated with dithiothreitol before assayed for IgG-RF, to abolish false-positive reactions due to IgM-RF activity. The detection limit for IgM-RF was 1 IU/ml. IgM-RF titers of 9 occurred in 7% of healthy adults and 73% of rheumatoid patients, titers .gtoreq. 18 in 3.5% and 67%, respectively. IgG-RF titers of 9 occurred in 9% of healthy adults, 21% of seronegative and 24% of seropositive rheumatoid patients. Titers of 18 occurred in 3% of healthy adults and in 14% of seronegative rheumatoid patients. Titers of .gtoreq. 18 occurred in 22% of seropositive rheumatoid patients. IgG-RF was correlated with an involvement of more than 20 joints. IgA-RF was found in 83% of seropositive, 11% of seronegative rheumatoid patients and in none of the healthy adults (serum dilution 1:9).