Risk assessment and immunotoxicity

Effects of a drug on the immune system can be assessed in humans but whether such effects result in decreased resistance to infections cannot easily be assessed in a direct sense. Extrapolation of data on immunotoxicity of agents resulting in decreased resistance to infections gathered from experiments with rodents to the human situation is, therefore, an important step for risk evaluation. This report describes the so-called parallellogram approach that can be used for this purpose. In this parallellogram there are four cornerstones, of which one is the health effect of exposure to a chemical, assessed as an endpoint (ie, infection model) in experimental animals, and another is the quantitative prediction of this endpoint in humans. The other cornerstones are assays that can be carried out both in experimental animals and humans or materials obtained from experimental animals and humans, and that are used for species comparison. For the immunotoxic agent ultaviolet light B radiation, and the environmental contaminant 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin this approach was used. Such studies may direct risk evaluation for immunotoxicity of drugs.