Ambient level ozone effects on subpopulations of thymocytes and spleen T lymphocytes.

The effects of ozone on thymocyte and spleen T lymphocyte subpopulations were studied. Balb/c mice were exposed to clean air or to 0.3 +/- 0.05 ppm ozone for 1-3 wk. Thymocytes and spleen T cells were stained with fluorochrome conjugated monoclonal antibodies against surface differentiation markers and/or propidium iodide for deoxyribonucleic acid (DNA). The cells were then analyzed by fluorescence activated cell sorter. The percentages of certain thymocyte and spleen T lymphocyte subtypes and DNA synthesizing spleen T cells were lower following 1 wk of ozone exposure. After 3 wk exposure, the thymocyte percentages were higher in ozone-exposed mice, whereas the absolute number remained lower, and spleen T lymphocytes showed no changes. The findings suggest that short-term ozone inhalation can affect the T cell immune system adversely, particularly the CD4+ cells.