Vitro Approaches to Test Various Aspects of Immunotoxicity

In Vitro Approaches to Test Various Aspects of Immunotoxicity 18.2.2.1 Introduction 

The immune system is complex, as it is not confined to one or several organs, but rather spread throughout the body. In addition, it involves delicate interactions between different cell types that vary not only between different locations but also in space and time after a toxic or pathologic insult. The various types of immunotoxicity differ considerably in the complexity of the mechanisms they affect. Therefore, also the phase of development of in vitro testing differs considerably between the various types of immunotoxicity. 

Immunosuppressive activity largely affects thymocytes and (im)mature T-cells and thus lymphocyte cultures are a rather straightforward model to assess immunosuppressive activity. Thymocyte cultures are also used, but may be less amenable to routine in vitro testing (Table 18.4). 

Although chemical sensitization is a more complex process than immunosuppression, by far most of the efforts on developing in vitro assays are in this field. An important reason for this is that from the various fields of immunotoxicity, most of the animals are used for sensitization testing. In fact the number of animals required for sensitization is second only after developmental toxicity testing. 

Intracellular cytokine levels Surface marker expression Gene expression Protein expression Signal transduction 

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