Immune system development Developmental immunotoxicity

The chemicals examined for developmental immunotoxicity in the mouse and rat encompasses a range of classes that include metals, pesticides, drugs, and aromatic hydrocarbons. Suppression of immune function was observed in adult rodents exposed to each of these chemicals during immune system development. The duration of immune function suppression in rodents so exposed ranged from 3 weeks (i.e., DOTC and MXC) to 19 months (i.e., TCDD) after the last exposure to the chemical. 

If one examines immune development, there are specific functionally distinct windows during which the immune system might be expected to have different susceptibilities based on critical biological events. By defining functionally distinct immune developmental windows, it is possible to make direct comparisons of differential immunotoxic susceptibilities using exposure assessment. 

Immunosuppressant exposure also impacts the development of the immune system. Several studies have shown this effect, 121318 including one that examined TCDD, described in the study as a notorious immunotoxicant. 121 Other chemicals that cause developmental immunotoxicity include PCBs,... 

Developmental immunotoxicity testing has gained increasing attention with the recognition that for most drugs compared to date, when immunomodulatory effects are observed, the developing immune system is more sensitive than that of the adult. Therefore, safety limits for exposure of non-adults can be difficult to predict in the absence of age-relevant exposure assessment. 

As has been seen with other toxic effects of Pb, there appear to be temporal and developmental windows for immunotoxic response. The developing immune system is 3—10 times more sensitive than the developed one. Sarasua et al. (2000) observed children 6—35 months of age who had statistically increased IgA, IgM, and B cell abundances. 

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