Abstract
Recently, interest has centered on the immune system as a target organ for toxic effects. This seems a reasonable choice, since it can be argued that alterations induced in this system as a result of a toxic insult could lead to impaired immunity. Such an alteration may be manifest in altered disease susceptibility. Documenting toxic effects upon the immune system is a difficult task due to the multifaceted network of specialized cells that carry out immune functions. Because of this complexity, it is necessary to develop a panel of immunologic assays to adequately cover the diverse functions that may be affected by a toxic substance. In the interest of efficiency and cost, it is preferable to organize the assay systems into a tier structure to generate the most information in the shortest time. An overview of the immune system is presented, an an example of one possible tier system of assays is described.