[(Fab')2-antiglobulins in serum and synovial fluid in patients with chronic polyarthritis].

In addition to the well-known rheumatoid factors or antiglobulins belonging to different immunoglobulin classes, a new type of antiglobulin has been found in serum and synovial fluid from patients with rheumatoid arthritis. 15/20 sera and 6/6 synovial fluids contained serologically active material with a molecular weight of approximately 95.000 Daltons. Using chromatographic and affinity chromatographic methods as well as specific precipitation techniques, the (Fab')2 character of these antiglobulins could be ascertained. These antiglobulins may arise through enzymatic degradation of IgG or monomeric IgM antiglobulins, or may be the product of partial intracellular degradation of phagocytosed immune complexes with subsequent extrusion of such material. An in vitro blocking effect of (Fab')2 type antiglobulins on SCMC or ADCC reactions was not found.