BLOODBORNE MARKERS IN HUMANS DURING MULTIDAY EXPOSURE TO OZONE

Intermittent exposure of the human lung to ambient levels of ozone (O- 3) was assayed in systemic fluids by using serum alpha-tocopherol (ST) as a gauge of oxidative stress and the blastogenic activity of periph eral blood monocytes as an index of immune function. Healthy men (n = 10) were evaluated over 3 consecutive days (130 min/day) of chamber ex posure to O-3 and filtered air (FA); subjects alternated between rest and light treadmill exercise during exposures. For O-3, the level was varied at 20-min intervals, i.e., 250, 350, 450, 450, 350; and 250 par ts/billion, and concluded with 10 min at 250 parts/billion. ST was qua ntitated by high-performance liquid chromatography techniques, and T-l ymphocyte blastogenesis was measured in cell cultures of peripheral bl ood monocytes by comparing [H-3]thymidine incorporation in mitogen-sti mulated (concanavalin A) and nonstimulated cells. After the third day of O-3 at 20 h postexposure, ST levels were reduced significantly comp ared with the FA control subjects (down 14%; -0.96 mu mol/l). Mitogen- activated T lymphocytes exhibited a 61% increase in blastogenic activi ty after 3 days of O-3 exposure, significant compared with the prolife rative activity of activated T lymphocytes collected after FA or befor e O-3 Acute airway function was impaired by O-3, e.g., on day 1, the f orced vital capacity and forced expiratory volume in 1 s were decrease d 8% (-0.92 liter) and 14% (-0.86 1/s), respectively, from preexposure values, and full recovery was delayed beyond 24 h. Effects of O-3 exp osure on cellular and biochemical markers increased in magnitude after each exposure and did not parallel the apparent adaptability of bronc hial sensitivity to O-3.