Drug and rheumatoid factor effects on the uptake of immunoglobulin g aggregates by neutrophil monolayers

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Abstract
This study examines aggregate-cell interactions in a newly applied neutrophil monolayer system, as an in vitro model of rheumatoid inflammation. Insoluble and soluble immunoglobulin G (IgG) aggregates were combined with rheumatoid factor (RF) to produce IgO-RF complexes. The presence of RF did not significantly change the uptake of the insoluble aggregates by neutrophils as measured in the monolayer system. Neutrophils exposed to these aggregates showed significantly (P< 0.05) greater uptake than those exposed to soluble aggregates, and the presence or absence of serum did not change these results. Increasing concentrations of radiolabeled aggregates to 1.5 mg/ml and cells to 5 × 106 neutrophils/ml increased cell-associated radioactivity. Addition of cytochalasin B to 5 mg/ml progressively depressed cell-associated radioactivity. Gold, but not aspirin, in therapeutic concentrations seemed to suppress aggregate uptake. This system offers a method for quantitatively assaying aggregate uptake which may be an important component of the rheumatoid inflammatory process.