The effects of ozone on immune function

A review of the literature reveals that ozone (O₃) exposure can either suppress or enhance immune responsiveness. These disparate effects elicited by O₃ exposure depend, in large part, on the experimental design used, the immune parameters examined as well as the animal species studied. Despite the apparent contradictions, a general pattern of response to O₃ exposure can be recognized. Most studies indicate that continuous O₃ exposure leads to an early (days 0-3) impairment of immune responsiveness followed, with continued exposures, by a form of adaptation to O₃ that results in a reestablishment of the immune response. The effects of O₃ exposure on the response to antigenic stimulation also depend on the time at which O₃ exposure occurred. Whereas O₃ exposure prior to immunization is without effect on the response to antigen, O₃ exposure subsequent to immunization suppresses the response to antigen. Although most studies have focused on immune responses in the lung, numerous investigators have provided functional and anatomical evidence to support the hypothesis that O₃ exposure can have profound effects on systemic immunity.