Immunotoxicity assessment: screening and function studies.

As a screening procedure to detect immunotoxic effects, different parameters are discussed. These criteria include growth, weight and histology of lymphoid and endocrine organs, haematology, as well s serum immunoglobulin concentrations which can be quantified using the enzyme-linked immunosorbent assay (ELISA). Secondly, different function tests are discussed to assess in the rat the cell-mediated immunity, the humoral immunity and the phagocytosis by macrophages. These tests should be performed when in a screening study an indication of immunotoxicity is found at a relevant dose level. The aim of functional assessment is to determine the functional significance of an effect on the immune response and to gain more insight into the mode of action of the chemical. Finally, examples are given of compounds that suppress or stimulate immune responses; and advantages are discussed of performing function tests during the development phase of the immune system.