Immunoglobulin complexes in sera of patients with malignancy.

Sera frour 146 patients with malignancy, 59 normal controls and 42 patients hospitalized with non-malignant diseases were examined by a precipitin test with monoclonal rheumatoid factor (mRF) for the presence of circulating immune complexes containing IgG. Forty-two (29%) of the sera from cancer patients but only two of the sera from patients in each of the control groups contained such material. Similar results were obtained with a radioimmunoassay for immune complexes based on the same mRF. Sera from 23 of 65 patients with metastatic malignancy (35%) had elevated levels of immune complexes by this latter test. The presence of the material was not related to the source of malignancy, presence of carcinoembryonic or hepatitis antigens or of such autoantibodies as rheumatoid factor or anti-DNA. By density gradient ultracentrifugation the reacting material was identified as being of molecular size 19s or greater. It has not yet been further characterized with regard to the nature of any antigens present.

Immune complexes in sera and synovial fluids of patients with rheumatoid arthritis. Radioimmunoassay with monocylonal rheumatoid factor.

Evidence for the presence of immune complexes in blood, synovial fluid, and tisues of patients with rheumatoid arthritis (RA) includes low complement levels in blood and effusions, deposition of immunoreactants in tissues and vessel walls, precipitate formation after addition of monoclonal rheumatoid factor (mRF) to serum or synovial fluid. To quantitate immune complex-like material in RA patients, we developed a radioimmunoassay based on inhibition by test samples of the interaction of (125I)aggregated IgG (agg IgG) and mRF coupled to cellulose. This method could measure immune complexes of human antibody with hemocyanine prepared in vitro. The assay was not influenced by presence of polyclonal RF in test samples, nor by freezing and thawing. Normal levels of immune complex-like material in serum were less than 25 mug agg IgG EQ/ML. 12 of 51 RA sera examined (26%) contained more than 25 mug/ml. The presence of this material in RA sera was found to correlate with severity of disease, as measured by anatomical stage and functional class. There was an inverse correlation of the material with serum C4 level. Rheumatoid synovial fluids generally contained higher levels than serum, and five of 23 contained very much higher levels. The frequency of elevated levels of immune complex-like material in sera of patients with systemic lupus erythematosus (2 of 29) and with miscellaneous vasculitides (2 of 21 was much lower than in RA, suggesting that mRF exhibits a specificity for only certain kinds of immune complexes. The reason for this apparent specificity may explain such distinctive features of RA as the high frequency of polyclonal RF, the lack of immune complex nephritis, and the generally normal levels of serum complement.