Activation of Lymphocytes in the Pulmonary Inflammatory Response to Silica

Abstract

Lymphocytes were separated from the parenchymal lung tissue of mice administered either silica or titanium dioxide particles by intratracheal injection. There was an approximately 10-fold increase in the number of T-lymphocytes recovered from silica-treated animals at 2 weeks after injection. This was accompanied by an increase in the percentage of separated cells expressing the interleukin-2 receptor and by enhanced spontaneous DNA synthesis in serum-free culture. No such changes were demonstrable in cells obtained from animals administered titanium dioxide. These results confirm that an influx of T-lymphocytes occurs as part of the early pulmonary inflammatory response to silica particles. Furthermore, lymphocytes in the lung are functionally activated by at least two criteria. Activated T-lymphocytes may play a role in the induction of fibroblast proliferation and collagen synthesis that occurs in silicotic lung disease.