Multispecificity of monoclonal rheumatoid factor.

The study involved a monoclonal rheumatoid factor referred to as RF-AN, obtained by Steinitz and his associates from IgG-reactive human lymphocytes 'immortalized' by infection with Epstein-Barr virus. RF-AN combined with red blood cells (RBC) sensitized by either human or rabbit IgG antibodies. The monoclonal character of RF-AN strongly suggested that the same molecule of this factor combined with IgG of both species.

Lack of circulating immune complexes in inflammatory bowel disease.

Multi-organ involvement and especially extraintestinal manifestations have suggested an immune complex-mediated pathogenesis of ulcerative colitis and Crohn's disease. Using various techniques controversial data have been reported on the incidence and levels of circulating immune complexes and their correlation to clinical presentation. Sera of 131 patients with inflammatory bowel disease (78 Crohn's disease, 53 ulcerative colitis) representing a wide spectrum of disease activity, treatment and presence or absence of extraintestinal manifestations were tested for circulating immune complexes using Raji cell indirect immunofluorescence assay, Raji cell radioimmunoassay, C1q solid phase assay and polyethylene glycol precipitation coupled with measurements of optical density and subsequent immunoelectrophoresis or radial immunodiffusion.

Are cross-reacting natural antibodies multispecific?

Human natural antibodies to antigens of Escherichia coli and Serratia marcescens were studied for cross-reactivity. The organisms were grown on synthetic media and extracted at 100 degrees C. The extracts were precipitated three times at 71% ethanol concentration and redissolved at the desired concentration.

Comparison of some procedures detecting circulating immune complexes.

Tests for circulating immune complexes were performed by means of 1) plain polyethylene glycol (PEG) precipitation (PEGprec), 2) immunoelectrophoresis of PEG precipitates (IEpp), 3) anti-antibody (AA) inhibition test with sera (AA-Is), and 4) AA inhibition test with PEG precipitates (AA-Ipp). The tests were performed with 156 pathological sera from patients with myasthenia gravis, syphilis, adenocarcinomas of the gastrointestinal tract, rheumatoid arthritis and systemic lupus erythematosus, and 51 normal sera from blood donors. PEGprec was positive with 76 sera, IEpp with 84 sera, AA-Is with 64 sera, and AA-Ipp with 74 sera.

Circulating immune complexes in systemic scleroderma.

Circulating immune complexes were detected by the immunoelectrophoretic method in 18 of 29 (62 per cent) of patients with systemic scleroderma. The presence of immune complexes did not correlate with that of antinuclear antibodies to dsDNA, DNP, RNP, and Sm. The mean levels of immunoglobulins G, A, and M as well as of C3 were significantly higher in patients with systemic scleroderma than in blood donors.

Monoclonal gammopathies in rheumatoid arthritis.

A total of 2560 sera from patients with and without rheumatoid diseases were examined for the incidence of monoclonal proteins. The incidence of monoclonal protein was higher (3.3%) in patients with rheumatoid arthritis than with other non-rheumatoid diseases of connective tissue (0.