EFFECT OF SULFUR-DIOXIDE ON CYTOKINE PRODUCTION OF HUMAN ALVEOLAR MACROPHAGES IN-VITRO

Tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, and tr ansforming growth factor-beta are cytokines synthesized by alveolar ma crophages. We investigated the effect of sulfur dioxide, a major air p ollutant, on the production of these cytokines by alveolar macrophages . The cells were layered on a polycarbonate membrane and exposed for 3 0 min to 0.0, 1.0, 2.5, and 5.0 ppm sulfur dioxide at 37 degrees C and 100% air humidity. The cells were incubated for 24 h after exposure, thus allowing cytokine release. Cytotoxic effects of sulfur dioxide we re evaluated by trypan blue exclusion. Cytokines were measured with en zyme-linked immunosorbent assays (i.e., tumor necrosis factor-alpha, i nterleukin-1 beta, and interleukin-6) or by use of a specific bioassay (i.e., transforming growth factor-beta). The toxicity of sulfur dioxi de for alveolar macrophages ranged from 3.1% to 9.5%, A 30-min exposur e to sulfur dioxide induced a significant decrease in spontaneous and lipopolysaccharide-stimulated tumor necrosis factor-alpha (p < .001) a nd lipopolysaccharide-stimulated interleukin-1 beta release (p < .05). The release of interleukin-6 and transforming growth factor-beta was not affected significantly by sulfur dioxide exposure. Our results dem onstrated a functional impairment of alveolar macrophages after sulfur dioxide exposure (i.e., release of tumor necrosis factor-alpha and in terleukin-1 beta). Neither spontaneous nor stimulated release of inter leukin-6 and transforming growth factor-beta were influenced by exposu re to sulfur dioxide.