ABSTRACT
This chapter discusses the effects of NO2 on host defenses in the experimental animals using models in which exposed animals are challenged with viable microbes and mortality is measured. The effects of NO2 on systemic humoral and cell-mediated immunity will be summarized in an attempt to speculate on immunological effects that might occur in the lung. The toxicological data base that has evolved from infectivity model studies using mice demonstrates that variations in concentration, length of exposure, and pattern of exposure are important factors in the determination of effects of NO2. The systemic humoral and cell-mediated immune system is susceptible to NO. However, the current difficulties in interpreting the magnitude of the immunological changes in animals in terms of human health inhibit hazard assessment. Additional studies are needed to help elucidate the effects of NO2 on lung host defenses. If human alveolar macrophages encounter a sufficient dose-rate of NO2, there is no apparent reason why they would not be affected.
