Response of perifused alveolar macrophages to glass fibers: effect of exposure duration and fiber length.

The effect of glass fibers on rat alveolar macrophages was studied with a new perifusion technique which allows the sequential determination of cell-derived inflammatory mediators as well as estimation of cell viability and aggregation at the end of the incubation period. Our results showed that glass fibers induced dose-dependent release of prostaglandins and beta-glucuronidase from macrophages and the aggregation and death of these cells. These deleterious effects were clearly related to the length of the fibers, with the longer fibers (greater than or equal to 4-5 micron) being more active than the shorter ones (less than 3 micron). Furthermore, a short exposure of 1 hr followed by an 18-hr perifusion induced the same inflammatory and toxic effects on the macrophages as did leaving the fibers undisturbed for the complete 18-hr perifusion. It is concluded that glass fibers produce effects in cultures of rat alveolar macrophages qualitatively similar to those of asbestos, and that fiber length appears to be a critical determinant of toxicity.