[Critical study of techniques for the detection of "light" rheumatoid factors (author's transl)].

In a number of cases of true rheumatoid arthritis, it is not possible to demonstrate the presence of 19 S "heavy" rheumatoid factors by the Waaler-Rose and globulin latex techniques. However, in some of them, 7 S rheumatoid factors are suspected. Three techniques for the detection of these "light" rheumatoid factors are described and critically evaluated. The authors report their own experience of the immuno-absorption and indirect immunofluorescence technique performed on 156 sera from RA patients. Immuno-absorption is not felt to be a reliable technique on several grounds. Indirect immunofluorescence is of value only in the diagnosis of seronegative rheumatoid arthritis where it provides information in addition to that offered by classical techniques. It is positive in 53.3% of seronegative rheumatoid arthritis sera.