Assessment of immunotoxic effects in humans.

The immunotoxic effects of chemicals are varied and markedly different depending on the underlying pathogenesis, namely, direct immunotoxicity (including immunosuppression, immunodepression, and immunostimulation), hypersensitivity, and autoimmunity. A large number of immunological endpoints and functional assays have been proposed for use as biomarkers of immunotoxicity, but they often lack sensitivity or are poorly standardized, so that their relevance in assessing immunotoxic effects in humans is at best ill established. Examining sentinel immunopathological events in individuals with a defined history of chemical exposure is another approach, presumably more cost-effective at the present time. A multicenter collaboration is mandated, however, because these events are rare. We expect that progress in new technologies, e.g., molecular biology, will provide the sensitive and reliable biomarkers of immunotoxicity that are currently lacking.